Development and validation of an UHPLC-Orbitrap-HRMS method for rapid determination of endogenous L-carnitine in patients on hemodialysis/peritoneal dialysis and its application to promote rational drug use.

Background: L-carnitine is an endogenous vitamin-like amino acid derivate which plays an essential role in energy metabolism and can be easily lost via dialysis. Deficiency of L-carnitine has great effects on many aspects of bodily functions. To determine the deficiency degree and adjust the supplementation dose, a rapid, sensitive, and specific method for the detection of endogenous L-carnitine in the plasma of dialysis patients using ultra-high performance liquid chromatography-Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-HRMS) was developed and validated. Methods: The plasma samples were processed by protein precipitation and centrifugation before analysis using UHPLC-Orbitrap-HRMS. Sample separation was achieved with a hydrophilic interaction liquid chromatography (HILIC) column, using an isocratic elution with a runtime of 5 min. The separated analytes were detected by positive ionization mode in full scan mode and targeted-single ion monitoring (t-SIM) mode. Mildronate was used as the internal standard (IS). Results: All the plasma could be detected in the range of 6.169 to 197.394 µM, with adequate accuracy, precision, and recovery. The method was validated in fortified validation with relative standard deviations (RSD) 5.15-8.74%. This method was applied to the analysis of 105 dialysis patients and 39 healthy participants, the results revealed that peritoneal dialysis patients without L-carnitine supplementation should pay more attention to L-carnitine monitoring, meanwhile, all the hemodialysis patients were advised to be routinely given a full dose of L-carnitine, no matter whether they had taken L-carnitine or not. Conclusions: This study developed a simple and rapid UHPLC-Orbitrap-HRMS method for detection of endogenous L-carnitine in dialysis patients, which could be useful to promote rational drug use.

Efficacy and Safety of Mulberry Twig Alkaloids Tablet for Treatment of Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Multicenter Clinical Study.

OBJECTIVE: To assess the efficacy and safety of mulberry twig alkaloids (Sangzhi alkaloids, SZ-A) for treatment of type 2 diabetes in a randomized, double-blind, placebo-controlled multicenter clinical trial. METHODS: A total of 200 patients were randomized to receive SZ-A (n=100) or placebo (n=100) for 16 weeks. The data analysis system for electronic data capture clinical trial central randomization system was used for randomization and dispensing of drugs. The primary outcome was the change in glycosylated hemoglobin (HbA1c) level. The secondary outcome included the proportions of cases with HbA1c <7.0% and HbA1c <6.5%, fasting blood glucose (FBG), postprandial blood glucose (PBG), area under curve for the PBG (AUC0-2h), body weight, and body mass index (BMI). Adverse events (AEs), severe adverse events (SAEs), treatment-related adverse events (TAEs), gastrointestinal disorders (GDs), blood pressure, routine blood tests, and liver and kidney function were monitored. RESULTS: Compared with baseline, the change of HbA1c at week 16 was -0.80% (95% CI: -0.98% to -0.62%) and -0.09% (95% CI: -0.27% to 0.09%) in SZ-A group and placebo group, respectively. The proportion of patients with HbA1c <7% and <6.5% was higher in the SZ-A group than in the placebo group (46.8% vs. 21.6% and 29.9% vs. 10.8%). The observed values and changes in FBG, 1 h-PBG, 2 h-PBG, and AUC0-2h differed significantly between groups (P<0.001), but differences were not significant in body weight and BMI (P>0.05). The incidence rates of AEs, TAEs, and GDs differed significantly between groups (P=0.010, P=0.005, and P=0.006, respectively), whereas the incidence rates of SAEs showed no significant differences between groups (P=1.000). CONCLUSION: SZ-A are effective and safe for treatment of type 2 diabetes. The protocol was registered in http://www.chictr.org.cn/showproj.aspx?proj=60117 (ChiCTR2000038550).

Berberine inhibits colorectal tumor growth by suppressing SHH secretion.

Hedgehog plays an important role in a wide range of physiological and pathological conditions. Paracrine activation of Hedgehog pathway in stromal cells increases the expression of VEGF, which promotes neovascularization in colorectal cancer and ultimately the growth of colorectal cancer. Berberine (BBR) has anticancer activity. In this study we investigated whether BBR inhibited the growth of colon cancer through suppressing the paracrine sonic hedgehog (SHH) signaling in vitro and in vivo. We showed that BBR (1-10 µM) dose-dependently inhibited the secretion and expression of SHH protein in HT-29 and SW480 cells. BBR did not influence the transcription of SHH, but promoted the degradation of SHH mRNA, thus decreased the SHH mRNA expression in the colorectal cancer cells. In nude mice bearing HT-29 xenograft, oral administration of BBR (100 mg · kg-1 · d-1) or a positive control drug GDC-0449 (100 mg · kg-1 · d-1) for 4 weeks markedly suppressed the growth of HT-29 tumor with BBR exhibiting a better antitumor efficacy. The tumor growth inhibition caused by BBR or GDC-0449 was comparable to their respective inhibitory effect on the mouse-specific Gli mRNA expression in the tumor. However, BBR (20 µM) did not affect the expression of human transcription factor Gli1 mRNA in HT-29 and SW480 cells. In conclusion, BBR promotes the degradation of SHH mRNA in colorectal cancer cells, interrupting the paracrine Hedgehog signaling pathway activity thus suppresses the colorectal cancer growth. This study reveals a novel molecular mechanism underlying the anticancer action of BBR.

The antiinflammatory effects of Xuefu Zhuyu decoction on C3H/HeJ mice with alopecia areata.

BACKGROUND: As a traditional and typical prescription of prominently activating blood circulation to remove blood stasis, Xuefu Zhuyu decoction (XZD) consists of 15 kinds of herbal medicine. Clinical investigations have showed that XZD could significantly promote the new hair generation of alopecia areata (AA) patients characterized by Qi stagnation and blood stasis. PURPOSE: The purpose of this study was executed to determine whether the mechanisms by which XZD stimulated newborn hair were related to its anti-inflammatory effects. METHODS: Clinical AA individuals were recruited to confirm the efficies of XZD. High performance liquid chromatography (HPLC) analysis was performed to qualitatively and quantitatively determine the contents of 15 compounds in XZD. Schrodinger molecular docking and in vivo surface plasmon resonance (SPR) techniques were used to evaluate the potential binding properties of compounds to target proteins. C3H/HeJ mice were randomly assigned to groups control, AA, and the XZD administration (6.5, 13.0 and 26.0 g/kg/d). Except for mice in control group, all the mice in the other groups were treated with a 21-day chronic unpredictable mild stress (CUMS) induced AA. Hematoxylin-eosin (H&E) staining was performed to determine the degree of pathological damage to the skin. Enzyme-linked immunosorbent assay (ELISA) was performed to detect levels of interleukin-6 (IL-6), interleukin-1 beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) and in serum and skin tissues. Western blot, immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were used to examine the expression levels of IL-6, IL-1ß, TNF-α and osteopontin proteins and genes in skin tissues. RESULTS: XZD could visibly promote hair regeneration of AA patients. The potential active ingredients in XZD prescription included at least amygdalin, hydroxysafflor yellow A, kaempferide, ferulic acid, catalpol, verbascoside, ß-ecdysone, platycodin D, paeoniflorin, naringin, neohesperidin, liquiritin, glycyrrhizic acid, saikosaponin A and saikosaponin D. The results of molecular docking and SPR analysis showed that verbascoside, liquiritin, kaempferide and amygdalin showed the best potential binding properties with IL-6, IL-1ß, TNF-α and osteopontin, respectively. Pathological evaluation showed that compared with the CUMS group, the administration of XZD significantly promoted hair regeneration, evidenced by increased number of skin hair follicles in C3H/HeJ AA mice. Compared with control group, ELISA data showed that the levels of IL-6, IL-1ß and TNF-α in serum and skin tissues of CUMS induced AA mice were significantly increased, while XZD administration dramatically restrained the contents of the three pro-inflammatory factors. Western blot, immunohistochemistry, and qRT-PCR results further demonstrated that XZD administration notably down-regulated the protein and gene expression levels of osteopontin, IL-6, IL-1ß and TNF-α in comparation with CUMS group. CONCLUSION: XZD could dramatically ameliorate CUMS-induced AA damage in the skin of C3H/HeJ mice, possibly by suppressing the levels of IL-6, IL-1ß, TNF-α and osteopontin.

The Chinese patent medicine, Jin-tang-ning, ameliorates hyperglycemia through improving ß cell function in pre-diabetic KKAy mice.

Jin-tang-ning (JTN), a Chinese patent medicine, mainly comprised of Bombyx moriL., has been proved to show α-glucosidase inhibitory efficacy and clinically effective for the treatment of type 2 diabetes (T2DM). Recently, we have reported that JTN could ameliorate postprandial hyperglycemia and improved ß cell function in monosodium glutamate (MSG)-induced obese mice, suggesting that JTN might play a potential role in preventing the conversion of impaired glucose tolerance (IGT) to T2DM. In this study, we evaluated the effect of JTN on the progression of T2DM in the pre-diabetic KKAy mice. During the 10 weeks of treatment, blood biochemical analysis and oral glucose tolerance tests were performed to evaluate glucose and lipid profiles. The ß cell function was quantified using hyperglycemic clamp at the end of the study. JTN-treated groups exhibited slowly raised fasting and postprandial blood glucose levels, and also ameliorated lipid profile. JTN improved glucose intolerance after 8 weeks of treatment. Meanwhile, JTN restored glucose-stimulated first-phase of insulin secretion and induced higher maximum insulin levels in the hyperglycemic clamp. Thus, to investigate the underlying mechanisms of JTN in protecting ß cell function, the morphologic changes of the pancreatic islets were observed by optical microscope and immunofluorescence of hormones (insulin and glucagon). Pancreatic protein expression levels of key factors involving in insulin secretion-related pathway and ER stress were also detected by Western blot. Pre-diabetic KKAy mice exhibited a compensatory augment in ß cell mass and abnormal α cell distribution. Long-term treatment of JTN recovered islet morphology accompanied by reducing α cell area in KKAy mice. JTN upregulated expression levels of glucokinase (GCK), pyruvate carboxylase (PCB) and pancreas duodenum homeobox-1 (PDX-1), while down-regulating C/EBP homologous protein (Chop) expression in pancreas of the hyperglycemic clamp, which indicated the improvement of mitochondrial metabolism and relief of endoplasmic reticulum (ER) stress of ß cells after JTN treatment. These results will provide a new insight into exploring a novel strategy of JTN for protecting ß cell function and preventing the onset of pre-diabetes to T2DM.

The Traditional Chinese Medicine Fuyou Formula Alleviates Precocious Puberty by Inhibiting GPR54/GnRH in the Hypothalamus.

The purpose of this study was to explore the effect of the traditional Chinese medicine Fuyou formula on precocious puberty (PP). The Fy formula may exert an effect in female rats with PP and GT-7 cells through the GPR54/GnRH signaling pathway. To confirm the effect of the Fy formula on PP through the GPR54/GnRH signaling pathway, we first treated GT1-7 cells with the Fy formula and observed changes in the expression of related genes and proteins and in GnRH secretion. Then, we randomly divided young female Sprague-Dawley rats into the control group, model group, leuprorelin group and the Fy formula group. A PP model was established by injection of danazol on postnatal day 5, and the Fy formula was administered on PND15. The time of vaginal opening, the wet weights of the ovary and uterus, serum hormone levels and the expression of hypothalamic-related genes were observed. We found that the Fy formula delayed vaginal opening, decreased the wet weights and coefficients of the ovary and uterus, decreased the levels of serum hormones (E2, follicle-stimulating hormone and luteinizing hormone) and the cellular GnRH level, and downregulated the gene expression of Kiss1, GPR54 and GnRH in the hypothalamus and the gene and protein expression of GPR54 and GnRH in GT1-7 cells. In conclusion, the Fy formula may alleviate PP via the GPR54/GnRH signaling pathway.

Berberine combined with stachyose induces better glycometabolism than berberine alone through modulating gut microbiota and fecal metabolomics in diabetic mice.

Berberine (BBR), a small alkaloid, is used as a hypoglycemic agent in China. Stachyose (Sta), a Rehmannia glutinosa oligosaccharide, acts as a prebiotic. This study aimed to evaluate whether BBR combined with Sta produced better glycometabolism than BBR alone, and explored the effects on gut microbiota and metabolomics. Type-2 diabetic db/db mice were administered BBR (100 mg/kg), Sta (200 mg/kg), or both by gavage once daily. Glucose metabolism, the balance of α- and ß-cells, and mucin-2 expression were ameliorated by combined treatment of BBR and Sta, with stronger effects than upon treatment with BBR alone. The microbial diversity and richness were altered after combined treatment and after treatment with BBR alone. The abundance of Akkermansia muciniphila was increased by combined treatment compared to treatment with BBR alone, while the levels of the metabolite all-trans-heptaprenyl diphosphate were decreased and the levels of fumaric acid were increased, which both showed a strong correlation with A. muciniphila. In summary, BBR combined with Sta produced better glycometabolism than BBR alone through modulating gut microbiota and fecal metabolomics, and may aid in the development of a novel pharmaceutical strategy for treating Type 2 diabetes mellitus.

[Advances in diabetic animal models and its application in the traditional Chinese medicine research].

The high and continuing soaring incidence of diabetes may become a huge obstacle to China's development. The antidiabetic drug development is one way to solve the problem. Animal model is a powerful tool for drug development. This paper compares and analyzes the three kinds of animal models for antidiabetic drug development in replicating principle, methods and characteristic, then summarized the application in the research of traditional Chinese medicine. At the same time, the analysis of the market, application and clinical advantages of hypoglycemic medicine from traditional Chinese medicine, is given in this paper, based on the literature analysis. From the point of the clinic advantage embodiment and new drug development, this paper will provide advisory and assistance support for the anti-diabetic fighting with traditional Chinese medicine.

A new thiophene and two new monoterpenoids from Xanthium sibiricum.

Three new compounds (1-3), together with six known compounds (4-9), were isolated from the fruits of Xanthium sibiricum. The structures and the absolute configurations of sibiricumthionol (1), (+)-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [(+)-2], ( - )-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [( - )-2], (2E,4E,1'S, 2'R, 4'S, 6'R)-dihydrophaseic acid (3), (+)-xanthienopyran [(+)-4] and ( - )-xanthienopyran [( - )-4] were established by extensive spectroscopic analyses, X-ray crystallographic analysis, ECCD analysis and ECD calculations. Caffeic acid (7) and caffeic acid ethyl ester (8) weekly inhibited α-glucosidase enzymatic activity by 44.5% and 40.2%, respectively, at 40 µM. Protocatechuic acid (9) selectively exhibited cytotoxicity against HepG2 cell lines, with an IC50 value of 2.92 µM.

Cyanogenetic glycosides and simple glycosides from the linseed meal.

Three new cyanogenetic triglycosides linustatins A-C (1-3), and two new simple glycosides linustatins D and E (4 and 5) were isolated from the 70% ethanol extract of flaxseed meal (Linum usitatissimum L.). Their structures were elucidated on the basis of spectroscopic analysis and chemical evidence. All of the isolates showed moderate activities against aldose reductase and weak activities against α-glucosidase, DPP-IV, and FBPase at the same concentrations as the positive control drugs.

[Effect of Mudan Granule on islets beta cell function in monosodium glutamate induced obese mice with insulin resistance: an experimental study].

OBJECTIVE: To study the effect of Mudan Granule (MD) on the glucose metabolism and beta cell function in monosodium glutamate (MSG) induced obese mice with insulin resistance (IR). METHODS: MSG obese mice were induced by subcutaneous injecting MSG (4 g/kg for 7 successive days in neonatal ICR mice). Forty MSG mice with IR features were recruited and divided into four groups according to body weight, fasting blood glucose, triglyceride (TG), total cholesterol (TC), and the percentage of blood glucose decreased within 40 min in the IR test, i.e., the model group (Con), the low dose MD group, the high dose MD group, and the Metformin group (Met). Besides, another 10 ICR mice were recruited as the normal control group (Nor). The water solvent of 2.5 g/kg MD or 5 g/kg MD was respectively administered to mice in the low dose MD group and the high dose MD group. Metformin hydrochloride was given to mice in the Met group at 0.2 g/kg body weight. Equal dose solvent distilled water was administered to mice in the Nor group and the Con group by gastrogavage, once per day. All medication was lasted for 15 weeks. Insulin tolerance test (ITT) and oral glucose tolerance test (OGTT) were performed after 6 weeks of treatment. Beta cell function was assessed by hyperglycemic clamp technique. The morphological changes in the pancreas were evaluated by hematoxylin-eosin (HE) staining. Changes of iNOS, NF-kappaB p65, and p-NF-kappaB p65 in the pancreas were tested. RESULTS: Compared with the Nor group, the blood glucose level, AUC, and fasting blood insulin, ONOO-contents, iNOS activities, and the expression of iNOS, NF-kappaB p65 subunit, pNF-kappaB p65 subunit obviously increased; decreased percentage of blood glucose within 40 min in ITT, glucose infusion rate (GIR), Clamp 1 min insulin, and Max-Insulin obviously decreased in the Con group (P < 0.05, P < 0.01). Compared with the Con group, the aforesaid indices could be improved in the Met group (P < 0.05, P < 0.01). In the low dose MD group, AUC, iNOS activities, and the expression of iNOS and p-NF-kappaB p65 subunit obviously decreased; percentage of blood glucose within 40 min in ITT and GIR obviously increased (P < 0.05, P < 0.01). In the high dose MD group, AUC, ONOO-contents, iNOS activities, and the expression of iNOS, NF-kappaB p65 subunit, and p-NF-KB p65 subunit obviously decreased; percentage of blood glucose within 40 min in ITT, Max-Insulin, and GIR obviously increased (P < 0.05, P < 0.01). CONCLUSION: MD could significantly improve IR and functional disorder of 3 cells in MSG obese mice, which might be associated with lowering inflammatory reaction in the pancreas.

A refined-JinQi-JiangTang tablet ameliorates prediabetes by reducing insulin resistance and improving beta cell function in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Refined-JQ (JQ-R) is a mixture of refined extracts from three major herbal components of JinQi-JiangTang tablet: Coptis chinensis (Ranunculaceae), Astragalus membranaceus (Leguminosae), and Lonicera japonica (Caprifoliaceae). Our previous studies have indicated that JQ-R could decrease fasting blood glucose levels in diabetic mice and insulin resistance mice. Investigating the hypoglycemic effect of JQ-R on prediabetes has practical application value for preventing or delaying insulin resistance, impaired glucose tolerance and possibly the development of clinical diabetes. MATERIALS AND METHODS: The anti-diabetic potential of JQ-R was investigated using a high fat-diet (HFD)-induced obesity mouse model. C57BL/6J mice (HFD-C57 mice) were fed with high-fat diet for 4 months. HFD-C57 mice were treated with either JQ-R (administered intragastrically once daily for 4 weeks) or metformin (as positive control), and the effects of JQ-R on body weight, blood lipids, glucose metabolism, insulin sensitivity, and beta cell function were monitored. RESULTS: The body weight, serum cholesterol, and the Homeostasis Model Assessment ratio (insulin resistance index) were significantly reduced in JQ-R or metformin-treated mice, and the glucose tolerance was enhanced and insulin response was improved simultaneously. Moreover, both JQ-R and metformin could activate liver glycogen syntheses even under a relatively high glucose loading. Although glyconeogenesis was inhibited in the metformin treated mice, it was not observed in JQ-R treated mice. Similar to metformin, JQ-R could also improve the glucose infusion rate (GIR) in hyperglycemic clamp test. JQ-R was also shown to increase the levels of phosphorylated AMPKα and phosphorylated acetyl CoA carboxylase (ACC), similar to metformin. CONCLUSION: JQ-R could reduce HFD-induced insulin resistance by regulating glucose and lipid metabolism, increasing insulin sensitivity through activating the AMPK signaling pathway, and subsequently improving ß cell function. Therefore, JQ-R may offer an alternative in treating disorders associated with insulin resistance, such as prediabetes and T2DM.

Potential anti-inflammatory constituents of the stems of Gordonia chrysandra.

Eight new oleanane-type triterpenoid glycosides, gordonosides I-P (1-8), and two new phenolic glycosides (9 and 10) were isolated from the stems of Gordonia chrysandra. Their structures were elucidated by spectroscopic and chemical methods. In an in vitro bioassay, compound 1 showed a strong inhibitory effect on nitric oxide production in LPS-activated macrophages with an IC50 value of 0.14 µM.

[Advances of the mechanism study on berberine in the control of blood glucose and lipid as well as metabolism disorders].

Berberine, an isoquinoline alkaloid isolated from some Chinese medicinal herbs such as Coptidis rhizoma, has been used for the treatment of diarrhea and other gastrointestinal infections as an antibacterial drug in Chinese medicine. In recent years, it was reported to have beneficial effects on the metabolism disorders states of diabetes. The mechanisms involve many aspects of the diabetes, including regulating the blood cholesterol and triglyceride, lowering blood glucose, ameliorating the insulin resistant state and influencing the function of the pancreatic beta cell.

[A novel cell model targeted on GLP-1 receptor for application to anti-diabetic candidates screening].

The aim of this project is to establish a GLP-1 signaling pathway targeted cell model, for screening the new class of GLP-1 receptor agonists as anti-diabetic candidates. Firstly construct a recombined plasmid with multi-copied specific response element (RIP-CRE) regulated by GLP-1 signaling pathway and E-GFP reporter gene. Transient transfect this recombined plasmid into islet cell NIT-1, then detect the responsibility of transfected cell to GLP-1 analogue, Exendin 4. For secondly, use stable transfection and monocloning cell culture to obtain a GLP-1 signaling-specific cell line. It indicates that this cell model can response to Exendin 4, which response can be completely inhibited by GLP-1 receptor antagonist, Exendin 9-39, further showing GLP-1 receptor specific activity with a cAMP-PKA-independently mechanism. Establishment of this novel cell model can be used in high-throughput drug screening of peptides or small molecular GLP-1 analogues.

A new screening method based on yeast-expressed human dipeptidyl peptidase IV and discovery of novel inhibitors.

Dipeptidyl peptidase (DPP) IV inhibitors provide a new strategy for the treatment of type 2 diabetes. Human DPP-IV gene was cloned from differentiated Caco-2 cells and expressed in Pichia pastoris. The recombinant enzyme was used in a new system for screening of DPP-IV inhibitors. By high throughput screening, a novel compound (W5188) was identified from 75,000 compounds with an IC(50) of 6.5 microM. This method is highly reproducible and reliable for discovery of DPP-IV inhibitors as shown by Z' value of 0.73 and S/N ratio of 6.89.

Is CCR7 a potential target for biologic therapy in psoriasis? Increased expression of CCR7 in psoriasis vulgaris.

BACKGROUND: Activated T cells present in psoriatic plaques play a key role in the pathogenesis of psoriasis. CCR7 on T cells plays a crucial role in native immune response and formation of secondary lymphoid organ. AIMS: To determine whether differential expression and functions of the CCR7 occur in psoriasis patients in China, we examined CCR7 on T cells from normal and psoriasis subjects. METHODS: Skin specimens and T cells from 33 patients and 22 healthy controls were analyzed by immunohistology, flow cytometry, and RT-PCR. RESULTS: Patients with psoriasis had a skewed distribution of T lymphocytes, with an increased level of CCR7+ T lymphocytes compared to healthy controls (P<0.01) By flow cytometry, it was found that CCR7 was selectively, frequently, and functionally expressed on CD4+ (20.5+/-6.8%)but not on CD8+ (9.5+/-3.4%) T cells from patients with psoriasis, whereas this phenomenon was not seen in normal subjects. Through RT-PCR it was also found that CCR7 was highly expressed on T cells in patients with psoriasis than in healthy controls in the level of gene. CONCLUSIONS: Patients with psoriasis had a skewed distribution of T lymphocytes, with an increased level of CCR7+ T lymphocytes compared to healthy controls. CD4+ CCR7+ T cells had abnormal expression, which might induce protraction and persistence of psoriasis.

Optimal frequency of treatment with the 308-nm excimer laser for vitiligo on the face and neck.

OBJECTIVES: This study was designed to determine the optimal treatment frequency with the 308-nm excimer laser for vitiligo and identify key clinical variable(s) associated with treatment efficacy at the optimal frequency. BACKGROUND DATA: Optimal clinical parameters for excimer laser treatment of vitiligo have not been fully determined. Data about the influence on treatment frequency of different clinical variables of vitiligo are needed to facilitate effective treatment regimens. METHODS: A total of 187 patients were treated with the 308-nm excimer laser for 20 sessions at different frequencies (0.5, 1.0, 2.0, and 3.0 per week). The repigmentation rate was graded on a six-point scale and was blindly evaluated by independent physicians. RESULTS: The final percentage of repigmentation for group 0.5 was statistically lower than those for group 1.0, 2.0, and 3.0, and percentages of final levels of repigmentation among these three groups were not statistically different. The clinical variables showed no statistical differences in the final repigmentation effect. Repigmentation occurred fastest with treatment frequencies of 2.0 and 3.0 and there was no statistically significant difference between them. The onset of repigmentation correlated with the area of vitiliginous patches treated, not with the other clinical variables. CONCLUSIONS: The 308-nm excimer laser is effective for therapy to treat vitiligo on the face and neck. The ultimate laser-induced repigmentation effect does not correlate with treatment frequency and repigmentation occurs faster with treatment frequencies of 2.0 and 3.0 than that of 1.0. It appears that the onset of repigmentation correlates with the total area of vitiliginous patches and the optimal treatment frequency. Monitored studies on a larger population with long-term follow-up would be needed to confirm and extend our findings.