Rationale for issuing neuroimaging requests for patients with primary headaches in China.

OBJECTIVE: To investigate the prevalence of neuroimaging in patients with primary headaches and the clinician-based rationale for requesting neuroimaging in China. DATA SOURCES AND STUDY SETTING: This study included patients with primary headaches admitted to hospitals and clinicians in China. We identified whether neuroimaging was requested and the types of neuroimaging conducted. STUDY DESIGN: This was a cross-sectional study, and convenience sampling was used to recruit patients with primary headaches. Clinicians were interviewed using a combination of personal in-depth and topic-selection group interviews to explore why doctors requested neuroimaging. DATA COLLECTION: We searched for the diagnosis of primary headache in the outpatient and inpatient systems according to the International Classification of Diseases-10 code of patients admitted to six hospitals in three provincial capitals by 2022.We selected three public and three private hospitals with neurology specialties that treated a corresponding number of patients. PRINCIPLE FINDINGS: Among the 2263 patients recruited for this study, 1942 (89.75%) underwent neuroimaging. Of the patients, 1157 (51.13%) underwent magnetic resonance imaging (MRI), 246 (10.87%) underwent both head computed tomography (CT) and MRI, and 628 (27.75%) underwent CT. Fifteen of the 16 interviewed clinicians did not issue a neuroimaging request for patients with primary headaches. Furthermore, we found that doctors issued a neuroimaging request for patients with primary headaches mostly, to exclude the risk of misdiagnosis, reduce uncertainty, avoid medical disputes, meet patients' medical needs, and complete hospital assessment indicators. CONCLUSIONS: For primary headaches, the probability of clinicians requesting neuroimaging was higher in China than in other countries. There is considerable room for improvement in determining appropriate strategies to reduce the use of low-value care for doctors and patients.

Classification of dark solitons via topological vector potentials.

Dark solitons are some of the most interesting nonlinear excitations and are considered to be the one-dimensional topological analogs of vortices. However, in contrast to their two-dimensional vortex counterparts, the topological characteristics of a dark soliton are far from fully understood because the topological charge defined according to the phase jump cannot reflect its essential property. Here, similar to the complex extension used in the exploration of the partition-function zeros to depict thermodynamic states, we extend the complex coordinate space to explore the density zeros of dark solitons. Surprisingly we find that these zeros constitute some pointlike magnetic fields, each of which has a quantized magnetic flux of elementary π. The corresponding vector potential fields demonstrate the topology of the Wess-Zumino term and can depict the essential characteristics of dark solitons. Then we classify the dark solitons according to the Euler characteristic of the topological manifold of the vector potential fields. Our study not only reveals the topological features of dark solitons but can also be applied to explore and identify new dark solitons with high topological complexity.

Multi-institutional Outcomes and Associations After Excision and Primary Anastomosis for Radiotherapy-associated Bulbomembranous Urethral Stenoses Following Prostate Cancer Treatment.

OBJECTIVE: To evaluate the outcomes of excision and primary anastomosis (EPA) for radiation-associated bulbomembranous stenoses using a multi-institutional analysis. The treatment of radiation-associated urethral stenosis is typically complex owing to the adverse impact of radiation on adjacent tissue. METHODS: An IRB-approved multi-institutional retrospective review was performed on patients who underwent EPA for bulbomembranous urethral stenosis following prostate radiotherapy. Preoperative patient demographics, operative technique, and postoperative outcomes were abstracted from 1/2007-6/2018. Success was defined as voiding per urethra without the need for endoscopic treatment and a minimum follow-up of 12 months. RESULTS: One hundred and thirty-seven patients from 10 centers met study criteria with a mean age of 69.3 years (50-86), stenosis length of 2.3 cm (1-5) and an 86.9% (119/137) success rate at a mean follow-up 32.3 months (12-118). Univariate Cox regression analysis identified increasing patient age (P = .02), stricture length (P <.0001) and combined modality radiotherapy (P = .004) as factors associated with stricture recurrence while body mass index (P = .79), diabetes (P = .93), smoking (P = .62), failed endoscopic treatment (P = .08) and gracilis muscle use (P = .25) were not. On multivariate analysis, increasing patient age (H.R.1.09, 95%CI 1.01-1.16; P = .02) and stenosis length (H.R.2.62, 95%CI 1.49-4.60; P = .001) remained associated with recurrence. Subsequent artificial urinary sphincter was performed in 30 men (21.9%), of which 25 required a transcorporal cuff and 5 developed cuff erosion. CONCLUSIONS: EPA for radiation-associated urethral stenosis effectively provides unobstructed instrumentation-free voiding. However, increasing stenosis length and age are independently associated with surgical failure. Patients should be counseled that further surgery for incontinence may be necessary.

[The association of fruit and vegetable intake with the changes of serum lipid levels in middle-aged and older Chinese population].

Objective: To investigate the association of fruit and vegetable intake with long-term changes of serum lipid levels in middle-aged Chinese and older Chinese population. Methods: The study analyzed the data collected in the 2004 and 2007-2008 cohorts of China Multicenter Collaborative Study of Cardiovascular Epidemiology. Finally, 4 495 participants from 10 groups in various regions of China, who both were followed up in the two cohorts, were included for data analysis. They were aged 41-66 years in 2004. Fruit and vegetable consumption were collected with a simple food frequency questionnaire. The percent changes (Δ%) of serum TC, TG, HDL-C and LDL-C between the two surveys were calculated. Multivariate linear regression models were used to estimate the association of fruit and vegetable intake in 2004 with percentage changes of serum lipid levels during the two surveys. Results: The proportions of individuals who consumed fruits <250, 250-499 and ≥500 g/week were 24.0%, 21.8% and 54.2%, respectively. The proportions of individuals who consumed vegetables <500 and ≥500 g/day were 76.7% and 23.3%, respectively. Compared with fruit intake <250 g/week, the regression coefficients (95% CI) of ΔTC% in 250-499 and ≥500 g/week group were -1.54 (-2.71, -0.37) and -1.77 (-2.79, -0.76). And the regression coefficients (95% CI) of ΔLDL-C% were -2.43 (-4.39, -0.48) and -2.89 (-4.59, -1.19). Compared with vegetable intake <500 g/d, the regression coefficients (95%CI) of ΔTC% and ΔLDL-C% in vegetable intake ≥500 g/d group were -1.01 (-1.95, -0.06) and -1.83 (-3.41, -0.24). However, fruit and vegetable intake had no relationship with ΔTG% and ΔHDL-C%. Conclusion: The consumption of fruit and vegetable was inversely related to long-term changes of TC and LDL-C in middle-aged and older population, but no association was found for changes of TG and HDL-C.

[Relationship between overnight urinary sodium to potassium ratio and the risk of cardiovascular disease].

Objective: To explore the relationship between overnight urinary sodium to potassium ratio and the risk of cardiovascular disease (CVD). Methods: A subsample of 10 percent of the participants (35-59 years old) from the People's Republic of China-United States Collaborative Study of Cardiovascular and Cardiopulmonary Epidemiology (prospective survey) were used. Three consecutive overnight urine samples were collected in the autumn of 1983-1984 and the spring in 1985-1986, respectively. Urinary sodium and potassium were detected and calculated for 8 hours excretion. The occurrences of cardiovascular events were recorded in 2 years interval from 1987-1988 until December 31, 2005. Participants were divided into first ratio group, second ratio group, and third ratio group based on the tertiles of sodium to potassium ratio. Cox proportional hazard regression model was used to determine the relationship between sodium to potassium ratio and risk of CVD. In addition, participants were divided into 2 subgroups by the median of overnight urinary sodium and potassium, and then combined each other for 4 subgroups including low sodium-low potassium group, low sodium-high potassium group, high sodium-low potassium group, and high sodium-high potassium group, to explore the relationship between different sodium-potassium combinations and the risk of CVD. Results: A total of 954 participants were included in the final analysis, of whom 459 (48.1%) were males. There were 318 cases in the first, second and third ratio group, respectively. There were 347 cases in low sodium-low potassium group and high sodium-high potassium group, and 130 cases in low sodium-high potassium group and high sodium-low potassium group. After a median follow-up of 18.6 (18.3, 19.3) years, cardiovascular events occurred in 81 participants, including 64 stroke and 20 coronary heart disease events. Multivariate analysis showed that comparing with the first ratio group, the hazard ratios (HR) in the second and the third ratio groups were 2.04 (95%CI 1.06-3.95, P=0.034) and 2.07 (95%CI 1.07-4.03, P=0.032), respectively. The CVD risk in low sodium-low potassium group was 24% higher than the low sodium-high potassium group (reference), but this result did not reach statistical significant level (P=0.685). The risks in high sodium-high potassium group (HR=3.32, 95%CI 1.26-8.76,P=0.015) and high sodium-low potassium (HR=3.04, 95%CI 1.05-8.83, P=0.041) group were both significantly increased. Conclusions: Overnight urinary sodium to potassium ratio is positively correlated with the risk of cardiovascular events. High urinary sodium plays a more important role for the increased risk of cardiovascular events than low potassium.

[Correlation of baseline serum interleukin-6, 10 and its ratio with 7-year all-cause mortality in 11 communities of Beijing].

Objective: To evaluate whether baseline interleukin-6 (IL-6), interleukin-10 (IL-10) as well as their ratio was associated with overall mortality risk over 7 years of follow-up in 11 communities of Beijing. Methods: Data from a prospective cohort study conducted between 2005 and 2012 in 11 communities of Beijing was analyzed to examine the above associations. Serum IL-6 and IL-10 were analyzed using enzyme-linked immunosorbent assay (ELISA) kits. Follow-up surveys were conducted in 2007, 2010 and 2012 to collect data about participant's survival. Cox regression model was used to estimate the impact of IL-6, IL-10 and their ratio on overall mortality risk. Results: Among 1 539 eligible participants (10 263 total person-years), 77 deaths occurred in 7 years of follow-up. The rates of all-cause death were 4.86, 7.24, and 10.56 per 1 000 person-years (P=0.009) in the first, second, and third tertile of IL-6, respectively. The corresponding age-sex-adjusted hazard ratios (HR) were 1.00, 1.18 (95% CI: 0.64-2.19), and 1.80 (95% CI: 1.01-3.23) and full-adjusted HR were 1.00, 1.17 (95% CI: 0.63-2.19) and 1.87 (95% CI: 1.04-3.36). The corresponding rates of all-cause deaths were not significantly different among three tertiles of IL-10. The age-sex and full-adjusted HR were not significantly different in Cox model. The rates of all-cause death were 4.63, 8.99, and 8.93 per 1 000 person-years (P=0.043) in the first, second, and third tertile of IL-6/IL-10 ratio, respectively. The corresponding age-sex-adjusted HR were 1.00, 1.67 (95% CI: 0.91-3.06), and 1.98 (95% CI: 1.08-3.64) and full-adjusted HR were 1.00, 1.66 (95% CI: 0.90-3.06), and 2.09 (95% CI: 1.13-3.87). Conclusion: High IL-6 and IL-6/IL-10 ratio may be new risk factors to all-cause death. However, IL-10 is not significantly associated with death.

Isolation and genetic characterization of a novel adeno-associated virus from Muscovy ducks in China.

Adeno-associated virus (AAV; genus Dependoparvovirus, family Parvoviridae) was first discovered in 1965 as a contaminant in adenovirus preparations. The AAVs are generally considered non-pathogenic, and they have the ability to attenuate the replication of other more pathogenic viruses, which makes them attractive as potential therapeutics or preventative measures. This study characterized a novel AAV isolated from Muscovy ducks in China. The novel virus (MHH-05-2015) was isolated after propagating a field isolate of the DAdV-3 virus (a type 3 duck adenovirus) in duck embryo fibroblasts. The full genome sequence of MHH-05-2015 was determined, and the nucleotide and amino acid sequences were compared to other avian AAVs. The genomic distribution of the structural and non-structural protein-coding genes in MHH-05-2015 was conserved and consistent with the other AAVs. Compared to previously isolated avian AAVs, MHH-05-2015 had approximately 63 to 64% sequence identity. Phylogenetic analysis indicated that MHH-05-2015 clustered separately from other avian AAVs, suggesting that MHH-05-2015 was not directly descended from other Dependoparvovirus family members. These results suggest that MHH-05-2015 is a new subtype of AAV that is distinct from other avian AAVs.

MicroRNA miR-590-5p inhibits breast cancer cell stemness and metastasis by targeting SOX2.

OBJECTIVE: SOX2 (Sry-related high-mobility box SOX-2) is a transcription factor, which is essential for maintaining the cancer cell stemness. However, the role of microRNAs targeting  SOX2 in cancer cell stemness remains unclear. We examined the effect of miR-590-5p, which targeted  SOX2, on the breast cancer cell stemness and metastasis. MATERIALS AND METHODS: We predicted and screened microRNA targeting SOX2, and further investigated the regulatory role of miR-590-5p on the level of SOX2 with Western blot, luciferase reporting assay and qRT-PCR analysis. Flow cytometry was performed to detect the effect of miR-590-5p on the breast cancer stem cell population with ALDEFLUOR Assay. We inoculated the breast cancer cells transfected with or without miR-590-5p to NOD/SCID mice to detect the tumorigenicity in vivo. Finally, forty-nine pairs of breast cancer samples and adjacent noncancerous tissues were obtained, and immunohistochemistry (IHC) with SOX2 antibody and qRT-PCR assay were used to quantify the expression of miR-590-5p in breast cancer samples. RESULTS: miR-590-5p significantly downregulated the SOX2 protein expression, and inhibition of miR-590-5p increased SOX2 expression. The luciferase reporter assay indicated that miR-590-5p decreased the SOX2 3'UTR (3' untranslated region) reporter activity but not the luciferase activity of the mutant reporter, in which the binding sites for miR-590-5p were mutated. ALDEFLUOR Assay showed that miR-590-5p significantly decreased breast cancer stem cells population. NOD/SCID nude mice experiments indicated that miR-590-5p significantly inhibited tumorigenicity of breast cancer cells. IHC assay and qRT-PCR suggested that miR-590-5p expression was downregulated in breast cancer patients, and negatively correlated with SOX2. CONCLUSIONS: miR-590-5p inhibited breast cancer cell stemness through targeting SOX2. Our study indicated that miR-590-5p might be a useful strategy for breast cancer treatment.

[Relationship between body weight status in early adulthood and body weight change to middle age and high-density lipoprotein cholesterol level in middle aged Chinese people].

OBJECTIVE: To explore the relationship between early adulthood weight status and body weight changes from early adulthood to middle age and high-density lipoprotein cholesterol (HDL-C) level. METHODS: Data were obtained from China Multicenter Collaborative Study of Cardiovascular Epidemiology Study, which was conducted in 1998, 15 participants population samples aged from 35-59 years old from 12 provinces were selected by random cluster sampling. Approximately 1 000 men and women in each sample population were surveyed for cardiovascular disease risk factors, body weight at age 25 from all participants were also obtained. Body mass index (BMI) at the age of 25 years was calculated with the weight at 25 years and the height measured during the survey, participants were divided into underweight (BMI<18.5 kg/m(2), n=1 331), normal-weight (18.5 kg/m(2)≤BMI <24 kg/m(2), n=10 400), overweight (24 kg/m(2)≤BMI<28 kg/m(2), n=2 019) and obesity (BMI≥28 kg/m(2), n=133) groups. Weight change was defined as the difference between the body weight at the age of 25 and at the survey and was grouped into<-7.5 kg (n=903), -7.5--2.6 kg (n=1 883), -2.5-2.5 kg (n=2 573), 2.6-7.5 kg (n=2 786), 7.6-12.5 kg (n=2 674) and>12.5 kg (n=3 064). The association of body weight status in early adulthood and body weight change from early adulthood to middle age with HDL-C level was examined by logistic regression model. RESULTS: The prevalence of low HDL-C in underweight, normal weight, overweight and obesity groups at age of 25 years were 10.7%(143/1 331), 15.5%(1 612/10 400), 16.3%(330/2 019) and 24.8%(33/133), respectively(P for trend <0.01). The prevalence of low HDL-C for adult weight change were 8.8%(79/903), 8.0%(151/1 883), 10.5%(269/2 573), 13.4%(373/2 786), 19.1%(511/2 674), and 24.0%(735/3 064)(P for trend <0.01)for weight change of <-7.5 kg, -7.5--2.6 kg, -2.5-2.5 kg, 2.6-7.5 kg, 7.6-12.5 kg and>12.5 kg, respectively. Multivariate logistic regression showed that overweight and obesity at age of 25 years and subsequent weight gain till middle age were positively correlated with low HDL-C after adjusted other risk factors(all P for trend <0.01). CONCLUSION: Overweight and obesity in early adulthood and significant adult weight gain from early adulthood to middle age were both independently associated with marked increases in the risk of low HDL-C in middle-aged Chinese men and women. Thus, body weight control at early adulthood could be a key strategy to reduce the incidence of low HDL-C at middle-aged population.

[Establishment and evaluation of a rat model of diabetes comorbid depression and its expression of glial fibrillary acidic protein in the brain].

OBJECTIVE: To establish and evaluate a rat model of diabetes comorbid depression, and observe alterations in expression of glial fibrillary acidic protein (GFAP) in several cerebral regions. METHODS: Eighteen Wistar rats were randomly divided into three groups, the control group (group CON, n=6), the diabetes mellitus group (group DM, n=6), and the diabetes comorbid depression group (group DD, n=6). Rats of group DM and group DD were injected intraperitoneally with STZ (64 mg/kg), the control rats received sham injections of citrate buffer alone. Group DD was then exposed to chronic unpredictable mild stress for 28 days. All rats were submitted to the open-field test and Morris water maze test immediately after the CUMS procedure. After brain tissue collection, the expression of GFAP in bilateral frontal cortex, hippocampus and hypothalamus were measured by immunohistochemistry. RESULTS: Rats of group DD and group DM exhibited classic diabetic signs of weight loss, hyperphagia, polydipia, gloomy hair and increasing urine and stool, group DD showed mental fatigue and slow response.The STZ-treated groups showed high blood glucose level (>33.3 mol/L) compared to the control group throughout the study. Group DD ((176± 11), (157±8), (154± 12)g)and group DM ((176±10), (161±8), (160±13)g)showed decline on body weight, whereas group CON ((245±14), (276±21), (314±25)g)showed continuously elevated body weight 0, 14, 28 days after CUMS.In behavioral tests, group DD ((4.1±3.1), (115±73), (26±13))showed reduced total traveling distance, activity time and times of locomotion compared to group CON ((9.3±3.2), (200±53), (40±11), P<0.05). Throughout the probe trial of Morris water maze test, group DD and group DM ((0.5±0.5), (0.5±0.6))performed less times of crossing the former platform area compared to group CON ((2.6±2.2), P<0.05). The mean optical density (MOD) of GFAP positive cells in frontal cortex, hippocampus and hypothalamus of group DD ((0.18±0.03), (0.19±0.02), (0.21±0.02)) were decreased compared with group DM ((0.26±0.03), (0.27±0.03), (0.30±0.04), P<0.01), but increased compared with group CON ((0.13±0.04), (0.15±0.02), (0.16±0.03), P<0.05 or P<0.01). CONCLUSION: Combination of intraperitoneally STZ injection and proper CUMS procedure can successfully build a rat model of diabetes comorbid depression. The expression of GFAP in bilateral frontal cortex, hippocampus and hypothalamus of group DD is significant different form group DM and group CON, which is helpful for understanding the pathogenesis of diabetes comorbid depression.

[Relationship between overweight/obesity and hypertension among adults in China: a prospective study].

OBJECTIVE: To evaluate the influence of overweight/obesity on the incidence of hypertension among adults in China. METHODS: The subjects of this prospective study were 13 739 Chinese adults aged 35-74 years recruited at the baseline surveys of China Multicenter Collaborative Study of Cardiovascular Disease Epidemiology and International Collaborative Study of Cardiovascular Disease in Asian. Baseline surveys were conducted in 1998 and during 2000-2001, respectively, and the follow-up was conducted during 2007-2008. According to the body mass index, the subjects were divided into four groups: underweight group(<18.5 kg/m(2)), normal weight group(18.5-23.9 kg/m(2)), overweight group(24.0-27.9 kg/m(2))and obesity group(≥28.0 kg/m(2)). Age-standardized cumulative incidence of hypertension was calculated for each group, respectively. The relative risks(RRs)and 95% confidence intervals(CIs)for the incidence of hypertension of underweight, overweight and obesity groups were estimated by using generalized linear regression model with normal weight group as reference. RESULTS: During 8.1 years of follow-up, 4 271 hypertension cases were detected(2 012 in men and 2 259 in women). Age-standardized cumulative incidence of hypertension for the underweight, normal weight, overweight and obesity groups were 20.3%, 30.9%, 43.6% and 50.8% in men, respectively; and 22.9%, 30.4%, 41.1% and 50.8% in women, respectively. Compared with the normal weight group, multivariate-adjusted RR(95% CI)for the incidence of hypertension in underweight, overweight and obesity groups were 0.78(0.64-0.95), 1.22(1.13-1.30)and 1.28(1.16-1.42)in men, respectively; and 0.89(0.77-1.03), 1.16(1.09-1.23)and 1.28(1.18-1.38)in women, respectively. The overweight and obese subjects had higher risk for the incidence of hypertension, with the population attributable risk proportion of 7.4% in men and 8.8% in women, respectively. CONCLUSION: Overweight or obese people are at an increased risk of developing hypertension, thus prevention and control of overweight/obesity are needed to reduce hypertension incidence among adults in China.

Long noncoding RNA HOTTIP contributes to the progression of prostate cancer by regulating HOXA13.

Prostate cancer is a leading cause of cancer-related mortality in men worldwide and there is a lack of effective treatment options for advanced (metastatic) prostate cancer. Long non-coding RNAs (lncRNAs) play important roles in diverse biological processes, such as cell growth, apoptosis and migration. However, little is known about the molecular mechanism of lncRNA-HOTTIP-mediated prostate cancer cell proliferation and apoptosis. The aim of this study was to elucidate the involvement of lncRNA HOTTIP in prostate cancer tumorigenesis and further investigate the role of HOXA13 in this process. Here, we showed that HOTTIP silencing inhibited cell survival pathway in vitro and in vivo by reducing the protein expression of Bcl-2 and enhancing Bax. We further demonstrated that knockdown of HOTTIP inhibited the expression of cell cycle regulatory protein Cyclin D1 and induced cell cycle arrest in G0/G1 phase. Additionally, depletion of HOXA13 by RNA interference (si-HOXA13) revealed that HOTTIP silencing suppressed cell growth at least partly through regulating HOXA13. In conclusion, down-regulation of HOTTIP and HOXA13 was associated with cell growth and cell cycle, and exerts tumor-suppressive functions in the genesis and progression of prostate cancer, providing a potential attractive therapeutic approach for this malignancy.

[Primary neuroendocrine carcinoma of the tonsil: two case reports and review of the literature].

Neuroendocrine carcinoma(NEC) of the tonsil is extremely rare. Only a few cases of this tumor have been reported so far. In this article, we described two patients presented with abnormal sensation of throat or throat pain. The pathological examination were NEC. With review of the literatures, the clinical characteristics were summarized and therapeutic strategies were discussed.

Metabolism of hydrogen peroxide between diapause and non-diapause eggs of the silkworm, Bombyx mori during chilling at 5 degrees C.

When diapause and non-diapause eggs of the same bivoltine strain of Bombyx mori were chilled at 5 degrees C for more than 30 days, the hatchability of diapause eggs increased while that of non-diapause eggs decreased, respectively. To investigate the relationship between effects of chilling on the hatchability and the metabolism of hydrogen peroxide (H2O2), content of H2O2 and activities of superoxide dismutase (SOD), xanthine oxidase (XO), and catalase (CAT) between diapause and non-diapause eggs were determined during the chilling at 5 degrees C. The significant enhancement of H2O2 occurred prior to the quick increase of the hatchability in diapause eggs and coincided with the quick decline of the hatchability in non-diapause eggs, respectively. Diapause eggs contained significantly higher H2O2 and XO activity and lower CAT activity compared to non-diapause eggs. Our results showed that there were significant differences in the metabolism of H2O2 between diapause and non-diapause eggs during chilling and that significant enhancement of H2O2 may be involved in the diapause termination of diapause eggs and the cell damage of non-diapause eggs.

Robotics in urologic surgery.

Robotic surgery is becoming rapidly integrated in urology. Nearly every open or laparoscopic procedure has been described with robotic assistance. While the da Vinci robot is recently applied to the upper urinary tract, it has become widely adopted for performing radical prostatectomy. Benefits of robotics include 3-D vision, blood-less field from pneumoperitoneum, and ease of intracorporeal suturing. Disadvantages include cost, lack of haptic feedback, surgical learning curve and longer operative times. Here, the authors describe the state of the art applications and outcomes of robotics in urologic surgery.

Nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition.

Nano-polycrystalline vanadium oxide thin films have been successfully produced by pulsed laser deposition on Si(100) substrates using a pure vanadium target in an oxygen atmosphere. The vanadium oxide thin film is amorphous when deposited at relatively low substrate temperature (500 degrees C) and enhancing substrate temperature (600-800 degrees C) appears to be efficient in crystallizing VOx thin films. Nano-polycrystalline V3O7 thin film has been achieved when deposited at oxygen pressure of 8 Pa and substrate temperature of 600 degrees C. Nano-polycrystalline VO2 thin films with a preferred (011) orientation have been obtained when deposited at oxygen pressure of 0.8 Pa and substrate temperatures of 600-800 degrees C. The vanadium oxide thin films deposited at high oxygen pressure (8 Pa) reveal a mix-valence of V5+ and V4+, while the VOx thin films deposited at low oxygen pressure (0.8 Pa) display a valence of V4+. The nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition have smooth surface with high qualities of mean crystallite size ranging from 30 to 230 nm and Ra ranging from 1.5 to 22.2 nm. Relative low substrate temperature and oxygen pressure are benifit to aquire nano-polycrystalline VOx thin films with small grain size and low surface roughness.

Characterization of the rapid proteolytic shedding of murine L-selectin.

The structural requirements for L-selectin shedding were studied in murine leukocytes. Upon activation, L-selectin on both lymphocytes and neutrophils undergoes cleavage by a membrane metalloprotease, resulting in the generation of a soluble ectodomain and a membrane-retained 6 kD fragment. Radiochemical sequencing demonstrated a cleavage site in the membrane-proximal region (MPR) between R321 and S322, which is homologous to the human site. Although intact neutrophil L-selectin is larger, it is cleaved at the same, or very close, site. Analysis of several transfectants expressing L-selectin point mutations and chimeric constructs suggest that, like human shedding, the proteolytic process has relatively loose sequence specificity for the substrate site. In addition, some constructs are susceptible to slow constitutive cleavage, but their shedding does not increase upon PMA stimulation, showing that basal and activated shedding are separable processes. Insertion of the 15 amino acid MPR into murine B7.2 conferred upon this molecule susceptibility to constitutive shedding. PMA stimulation results in little or no acceleration of down regulation of this molecule. These results suggest that recognition of both the membrane-proximal cleavage site and of a site distant from the MPR are required for maximal induction of L-selectin shedding.