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Biomedical subjects

X W Sun

Publications and source records attributed to X W Sun.

At least 19 recordsLinked to original sources
PubMed2006

Tunable superprism and polarization splitting in a liquid crystal infiltrated two-dimensional photonic crystal made of silicon oxynitride.

Tunable superprism and polarization splitting effects, based on liquid-crystal infiltrated two-dimensional photonic crystal with SiON as a background material, are demonstrated. Owing to the strong birefringence of the liquid crystal, the dispersion curves of the two polarizations are distinctly different, resulting in large splitting between the two polarizations. Extremely large splitting, as large as 80 degrees, can be obtained. Moreover, the splitting can be tuned to a substantial degree when the optic axis of the liquid crystal is reoriented. Fully controllable, incident-angle-dependent and wavelength-dependent superprism effects are also demonstrated. This large swing in the refraction can be completely switched off by reorientation of the optic axis of the liquid crystal, thus to resemble bulk media refraction.

Journal Article↗
PubMed2006

Symmetry properties of two-dimensional anisotropic photonic crystals.

A theoretical study of two-dimensional photonic crystals made of anisotropic material is presented. Detailed computation principles including a treatment of the TE and TM polarizations are given for a photonic crystal made of either uniaxially or biaxially anisotropic materials. These two polarizations can be decoupled as long as any one of the principal axes of the anisotropic material is perpendicular to the periodic plane of the photonic crystal. The symmetry loss due to the anisotropy of the material and the variation of the Brillouin zones relative to the tensor orientations are also analyzed. Furthermore, the symmetry properties of the two-dimensional photonic band structure are studied, and the resulting effect on the photonic bandgap and the dispersion properties of photonic crystal are analyzed as a function of the orientation of the anisotropic material.

Journal Article↗
PubMed2004

Generating doughnut-shaped beams with large charge numbers by use of liquid-crystal spiral phase plates.

Liquid-crystal spiral phase plates with cell gaps of 7 and 20 microm have been used to generate doughnut-shaped beams (doughnut beams) with charges of 1 and 4, respectively. Stacking these liquid-crystal spiral phase plates yielded doughnut beams with charge numbers up to 8. High efficiency and flexibility are the advantages of generating doughnut beams by stacking liquid-crystal spiral phase plates. Interference of doughnut beams generated by liquid-crystal spiral phase plates and plane waves has been studied. Fingerlike interference patterns were obtained with a doughnut beam tilted from a Gaussian beam; spiral fanlike patterns were obtained with a doughnut beam and a Gaussian beam collimated coaxially. The experimental results are supported qualitatively by simulation. By rotating a glass slide in the path of the Gaussian beam, one can rotate the fanlike interference pattern in a controlled fashion. With the liquid-crystal display technology that we have developed and report here, these liquid-crystal spiral phase plates should find applications in optical tweezers.

Journal Article↗
PubMed2001

[Transdermal delivery of cyclosporin A solubilized in mixed micelles through mice skin].

AIM: To investigate the transdermal delivery effects of cyclosporine A solubilized in mixed micelles composed of phospholipid and different surfactants. METHODS: When applied onto the excised abdominal skin of the mice occlusively, the enhancing effects of various mixed micelles on the penetration of cyclosporin A were assessed by an in vitro permeation technique. In vivo study was carried out by topical application of sodium cholate-phospholipid mixed micelles onto the mice skin and drug blood concentration was detected. RESULTS: In vitro, mixed micelles containing different surfactants displayed distinct permeability and corresponded to the following order: sodium cholate > sodium deoxycholate > Trition X-100 > Tween-20. In vivo, peak drug concentration was detected at 5 h and after that the concentration fell down slowly. CONCLUSION: Mixed micelles were shown to be efficient carrier for the transdermal delivery of the lipophilic polypeptide when kept in solution during the application process.

Administration, Cutaneous↗
PubMed2000

Incidence of cervical squamous intraepithelial lesions in HIV-infected women.

CONTEXT: Women infected with human immunodeficiency virus (HIV) are at increased risk for cervical squamous intraepithelial lesions (SILs), the precursors to invasive cervical cancer. However, little is known about the causes of this association. OBJECTIVES: To compare the incidence of SILs in HIV-infected vs uninfected women and to determine the role of risk factors in the pathogenesis of such lesions. DESIGN: Prospective cohort study conducted from October 1,1991, to June 30, 1996. SETTING: Urban clinics for sexually transmitted diseases, HIV infection, and methadone maintenance. PARTICIPANTS: A total of 328 HIV-infected and 325 uninfected women with no evidence of SILs by Papanicolaou test or colposcopy at study entry. MAIN OUTCOME MEASURE: Incident SILs confirmed by biopsy, compared by HIV status and risk factors. RESULTS: During about 30 months of follow-up, 67 (20%) HIV-infected and 16 (5%) uninfected women developed a SIL (incidence of 8.3 and 1.8 cases per 100 person-years in sociodemographically similar infected and uninfected women, respectively [P<.001]). Of incident SILs, 91% were low grade in HIV-infected women vs 75% in uninfected women. No invasive cervical cancers were identified. By multivariate analysis, significant risk factors for incident SILs were HIV infection (relative risk [RR], 3.2; 95% confidence interval [CI], 1.7-6.1), transient human papillomavirus (HPV) DNA detection (RR, 5.5; 95% CI, 1.4-21.9), persistent HPV DNA types other than 16 or 18 (RR, 7.6; 95% CI, 1.9-30.3), persistent HPV DNA types 16 and 18 (RR, 11.6; 95% CI, 2.7-50.7), and younger age (<37.5 years; RR, 2.1; 95% CI, 1.3-3.4). CONCLUSIONS: In our study, 1 in 5 HIV-infected women with no evidence of cervical disease developed biopsy-confirmed SILs within 3 years, highlighting the importance of cervical cancer screening programs in this population.

Adult↗
PubMed1999

Human immunodeficiency virus infection and female lower genital tract malignancy.

The risk of lower genital tract neoplasia is increased in women infected with HIV. This has been best demonstrated in cervical squamous intraepithelial lesions, but has also been observed in vulvar and perianal intraepithelial lesions in some studies. Alterations in the prevalence and natural history of human papillomavirus infections of the lower genital tract appear to account for much of the increase. HIV-infected women are approximately four times more likely to be infected with human papillomavirus (including infection with high oncogenic risk human papillomavirus types) than are HIV-uninfected women, and these infections are more likely to be persistent. Human papilomavirus-associated lesions may be more difficult to treat in HIV-infected women. These data highlight the need to develop effective cervical cancer prevention programs for HIV-infected women.

Anus Neoplasms↗
PubMed1998

Triage of women with ASCUS and LSIL on Pap smear reports: management by repeat Pap smear, HPV DNA testing, or colposcopy?

BACKGROUND: The purpose of this study was to determine the efficacy of a repeat Papanicolaou (Pap) smear and the Hybrid Capture tube-based (HCT) HPV DNA test for detecting cervical intraepithelial neoplasia (CIN) grade 2 or 3 in women with recent atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion (LSIL) Pap smear reports. METHODS: Women with a recent Pap smear report of ASCUS (n = 169) or LSIL (n = 110) had a repeat Pap smear, sampling of the cervix for HCT HPV DNA assay and a colposcopy examination. Data were evaluated using three different triage thresholds for colposcopy examination: a repeat Pap smear of persistent ASCUS or more severe dysplasia, a finding of persistent LSIL or more severe dysplasia, and a carcinogenic HPV test result. RESULTS: The sensitivity, specificity, and positive and negative predictive values for detecting CIN 2/3 were 70%, 45%, 7%, and 96% for a repeat Pap smear using an ASCUS-positive threshold and 20%, 86%, 8%, and 94% for a repeat Pap smear using an LSIL-positive threshold, respectively, when women with an initial ASCUS Pap smear were considered. HPV testing for carcinogenic viruses alone or in combination with a repeat Pap smear (using ASCUS as a positive threshold) yielded results of 50%, 67%, 9%, and 96%, respectively, and 70%, 37%, 7%, and 95%, respectively, for detecting CIN 2/3. In women with an initial LSIL Pap smear, respective values for detecting CIN 2/3 by a repeat Pap smear with an ASCUS threshold were 92%, 26%, 14%, and 96%, and for an LSIL threshold 23%, 64%, 8%, and 86%, respectively. Hybrid Capture HPV testing alone or in combination with a repeat Pap smear yielded 69%, 43%, 14%, and 91%, respectively, and 100%, 21%, 14%, and 100%, respectively. CONCLUSIONS: A Pap smear triage threshold restricted to LSIL or more severe dysplasia for women with prior ASCUS or LSIL Pap smear results was clearly ineffective for detecting high-grade cervical precancerous lesions. In contrast, when the repeat Pap smear triage threshold was expanded to include persistent ASCUS as abnormal, 83% of the women with CIN 2/3 were detected. Detection of carcinogenic HPV DNA using the HCT test was almost as sensitive for detecting CIN 2/3 as a solitary repeat Pap smear using an ASCUS or more severe positive threshold. Combining the HPV test with a repeat Pap smear did not significantly improve the sensitivity of cytology for detecting high-grade CIN. This study suggests that women with ASCUS and particularly LSIL Pap smears should be referred for a colposcopy examination until better triage methods become available.

Adult↗
PubMed1998

Comparison of two tests for detecting carcinogenic HPV in women with Papanicolaou smear reports of ASCUS and LSIL.

BACKGROUND: The detection of cancer-associated types of human papillomavirus (HPV) in cervical specimens predicts the presence and future development of cervical intraepithelial neoplasia (CIN). The purposes of this study were (1) to determine the efficacy of a second-generation assay by hybrid capture (HC II) to detect carcinogenic HPV from residual cervical cells of a liquid-based cervical cytologic specimen, and (2) to compare the performance of this second-generation test with the first-generation hybrid capture (HCT) HPV test of material from direct cervical sampling to detect CIN in women with atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesion (LSIL) Papanicolaou (Pap) smear reports. METHODS: Women with a recent Pap smear report of ASCUS or LSIL had a sampling of the cervix using either an Ayre's spatula and cytobrush or an Accellon device sampling for liquid-based cytologic system HC II HPV testing, followed by a Dacron swab sampling of the cervix for standard HCT HPV testing of the paired specimens. All women received colposcopy examinations including cervical biopsy and endocervical curettage, when indicated, to determine criterion standards for comparison. RESULTS: Paired swabs and liquid-based cervical specimens from 242 women were available for testing by standard HCT and the newer HC II HPV DNA assays. The sensitivity, specificity, and positive and negative predictive values for detecting CIN grade 2 or 3 (CIN 2/3) were 61.9%, 57.0%, 12.0%, and 94.0%, respectively, for the HCT test, and 90.5%, 29.4%, 10.9%, and 97.0%, respectively, for the liquid-based cytology HC II assay. When only women with an initial ASCUS Pap smear report were considered, the HC II test results were 88.9%, 40.3%, 9.1%, and 98.2%, respectively. CONCLUSIONS: Testing for lower genital tract carcinogenic HPV DNA using a cervical cytology liquid transport media residual sample is clinically feasible. The new HC II microplate HPV test achieved a greater test sensitivity for detecting carcinogenic HPV and correspondingly of CIN 2/3 compared with the currently available first-generation HC HPV test. Use of a liquid-based cervical cytology system combined with intermediate triage by HC II testing of residual cells for carcinogenic HPV alone may help to efficiently identify CIN 2/3 in women who have a prior screening Pap smear report of ASCUS.

Adult↗
PubMed1997

Human papillomavirus infection in women infected with the human immunodeficiency virus.

BACKGROUND: Among women infected with the human immunodeficiency virus (HIV), there is a high prevalence of human papillomavirus (HPV) infections. However, little is known about the natural history of HPV infections in HIV-seropositive women, and persistent HPV infections may explain the increased risk of cervical squamous intraepithelial lesions and invasive cervical cancer in HIV-seropositive women. METHODS: A total of 220 HIV-seropositive and 231 HIV-seronegative women in the New York City area were evaluated at two or more semiannual gynecologic examinations that included a Pap test, a test for HPV DNA, and colposcopy. RESULTS: HPV DNA was detected at the initial examination in 56 percent of the HIV-seropositive and 31 percent of the HIV-seronegative women. After four examinations, the cumulative prevalence of HPV infection was 83 percent in the seropositive women and 62 percent in the seronegative women (P<0.001). Persistent HPV infections were found in 24 percent of the seropositive women but in only 4 percent of the seronegative women (P<0.001). Twenty percent of the seropositive women and 3 percent of the seronegative women had persistent infections with HPV-16-associated viral types (16, 31, 33, 35, or 58) or HPV-18-associated types (18 or 45) (P<0.001), which are most strongly associated with cervical cancer. The detection of HPV DNA in women with previously negative tests was not associated with sexual activity during the interval since the preceding examination. CONCLUSIONS: HIV-seropositive women have a high rate of persistent HPV infections with the types of HPV that are strongly associated with the development of high-grade squamous intraepithelial lesions and invasive cervical cancer. These persistent infections may explain the increased incidence of squamous intraepithelial lesions in HIV-seropositive women.

AIDS-Related Opportunistic Infections↗
PubMed1997

Increased prevalence of vulvovaginal condyloma and vulvar intraepithelial neoplasia in women infected with the human immunodeficiency virus.

OBJECTIVE: To compare the prevalence of human papillomavirus (HPV)-associated vulvovaginal lesions in human immunodeficiency virus (HIV)-positive and HIV-negative women. METHODS: For this cross-sectional study, all participants received a complete gynecologic examination including colposcopic evaluation and a structured interview about sociodemographic characteristics and risk factors for vulvovaginal disease. In addition, HPV DNA was assayed for in cervicovaginal lavages using polymerase chain reaction. RESULTS: Vulvar and/or vaginal condyloma acuminata were detected in 22 of 396 (5.6%) HIV-positive and in 3 of 375 (0.8%) HIV-negative women (odds ratio [OR] 7.3, P < .001). High-grade vulvar intraepithelial neoplasia (VIN) was present in two of the HIV-positive and none of the HIV-negative women. Human immunodeficiency virus-positive women with condyloma or VIN were significantly more likely to have cervical intraepithelial neoplasia (33%) than those without vulvovaginal lesions (17%) (OR 2.9, 95% confidence interval [CI] 1.1, 74). In multivariate logistic regression analysis, both HIV seropositivity (adjusted OR 5.3, 95% CI 1.3, 35.3) and HPV infection (adjusted OR 6.1, 95% CI 1.7, 39.4) were associated with vulvovaginal condyloma. CONCLUSION: The prevalence of vulvovaginal condyloma was increased in HIV-positive women even when controlling for HPV infection. Human papillomavirus-associated disease was more likely to be multicentric and involve the vulva, vagina, and cervix in HIV-positive than HIV-negative women. Detection of high-grade VIN in two of the HIV-positive women suggests that they may also be at risk for developing invasive vulvar carcinoma.

AIDS-Related Opportunistic Infections↗
PubMed1996

Association between human papillomavirus type and clonal status of cervical squamous intraepithelial lesions.

BACKGROUND: Lesions that are histologically classified as precursors of cervical cancer, which are often referred to as squamous intraepithelial lesions (SILs), represent a heterogeneous clinical entity that can be associated with many different types of human papillomaviruses (HPVs) and have a variable biologic behavior. Approximately one half of low-grade SILs behave as non-neoplastic, productive viral lesions that frequently regress spontaneously, whereas the other half behave as neoplasms and either persist or progress to a histologically higher grade lesion. Identification of biomarkers that reliably differentiate those low-grade SILs with the properties of a non-neoplastic viral infection from those with the properties of neoplasia would provide a more rational basis for decisions about disease management. Since monoclonality is a hallmark of neoplasia irrespective or organ site, clonal status might represent one such biomarker. PURPOSE: To better understand the pathobiology of SILs, we analyzed the clonality of low-grade and high-grade SILs and compared their clonal status with their associated HPV types. METHODS: One hundred forty formalin-fixed, paraffin-embedded cervical biospy and loop electrosurgical specimens, originally diagnosed as SILs, were obtained from the pathology archives of both the Columbia-Presbyterian Medical Center and Kyto Diagnostics in New York. Clonality was determined with the use of a polymerase chain reaction (PCR) based method that detects nonrandom X-chromosome inactivation. This PCR-method amplifies a polymorphic region of the androgen receptor gene that is flanked by several differentially methylated enzyme sites. The same tissue was also analyzed for HPV DNA with the use of PCR and both L1 and E6 "consensus" primers. RESULTS: All 25 evaluable cases of high-grade SILs were determined to be monoclonal. Although 54 (68%) of 79 evaluable low-grade SILs were monoclonal, 25 (32%) of 79 low-grade SILs were polyclonal. A strong association was observed between HPV type and clonal status, with a total of 71 (47 low-grade and 24 high-grade) SILs determined to be monoclonal and containing HPV types 16, 18, 31, 33, 35, 39, 45, 56, 58, or 65. In contrast, 22 (92%) of the 24 low-grade SILs that contained another type of HPV were polyclonal (Fisher's exact test, two-sided, P</-.001). CONCLUSIONS: Our findings suggest that the histopathologic entity termed low-grade SIL consists of two different types of lesions that are biologically distinct. One lesion is monoclonal and is associated with HPV types 16, 18, 31, 33, 35, 39, 45, 56, 58, or 65. The second types of low-grade SIL is polyclonal and is associated with other types of HPV.

Alleles↗
PubMed1996

Invasive vulvar carcinoma in two women infected with human immunodeficiency virus.

This report presents two HIV-infected women who developed invasive squamous cell carcinoma of the vulva. One patient was diagnosed with Stage II vulvar cancer 4 years after surgical excision of VIN. This patient underwent a hemivulvectomy and external-beam radiation therapy, but has subsequently developed recurrent vulvar cancer. The other patient was diagnosed with stage IV invasive vulvar cancer 1 year after the diagnosis of VIN and died of invasive vulvar cancer 11 months later. VIN should be considered a serious condition in HIV-infected women and clinicians should be careful to examine the vulva and perianal region in all HIV-infected women.

Acquired Immunodeficiency Syndrome↗
PubMed1996

The etiology of lung cancer in nonsmoking females in Harbin, China.

A case-control study of female lung adenocarcinoma in Harbin, China involving interviews with 120 cases of nonsmoking females, matched 1:1 with controls, showed that high coal use, indoor air pollution, exposure to coal dust, frequent frying and deep frying food, and a history of lung cancer in the family were statistically significant risk factors for female adenocarcinoma. High personal income, spacious living quarters, and frequent consumption of carrots were protective factors for adenocarcinoma.

Adult↗
PubMed1996

Anogenital papillomavirus infection and neoplasia in immunodeficient women.

This article reviews the impact of infection with human immunodeficiency virus (HIV) on HPV infections and HPV-associated lesions of the female anogenital tract. Studies investigating HPV infections in HIV-seropositive women are presented as well as the possibility that HIV can influence HPV expression directly through molecular interactions between viral genes and indirectly through immunosuppression. Studies linking HIV infection to invasive cervical cancer and cervical intraepithelial neoplasia are reviewed; recommended protocols for cervical cancer screening in HIV-seropositive women for cervical disease also are presented.

Adolescent↗
PubMed1996

Prevalence of anal human papillomavirus infection and anal cytologic abnormalities in HIV-seropositive women.

OBJECTIVE: To determine the prevalence of anal human papillomavirus (HPV) infections and anal cytologic abnormalities in HIV-seropositive and HIV-seronegative women. DESIGN: This cross-sectional study of a cohort of women with known HIV serostatus involved a standardized interview and a gynecologic examination, including a cytologic evaluation of the cervix and anus. Anal swabs were tested for HPV DNA using the Hybrid Capture assay. SETTING: Two HIV/AIDS clinics, a sexually transmitted disease clinic, a methadone clinic and women enrolled in a study of HIV heterosexual transmission in the greater New York City metropolitan area. PATIENTS: One hundred and two HIV-seropositive and 96 HIV-seronegative women were selected from an ongoing study of the gynecologic manifestations of HIV infection. MAIN OUTCOME MEASURES: Detection of anal HPV DNA and anal cytologic abnormalities. RESULTS: Anal cytologic abnormalities were detected in 27 (26%) of the 102 HIV-seropositive women and in six (7%) of 96 HIV-seronegative women. Five (5%) of the anal smears from the HIV-seropositive women and one (1%) from the HIV-seronegative women had low-grade anal intra-epithelial neoplasia. The remainder of the anal cytologic abnormalities were classified as mild squamous cytologic atypia. HPV DNA was detected in 30 (29%) of 102 HIV-seropositive and two (2%) of 96 HIV-seronegative women. Of the 33 patients with anal cytologic abnormalities, 19 (58%) had anal HPV DNA detected as compared to 13 (8%) of 160 women without cytologic abnormalities (P < 0.001). In a multivariate logistic regression analysis, HIV-seropositivity was found to be an independent risk factor for both anal HPV infection and anal cytologic abnormalities and the strength of the association was greater in women with lower CD4+ T-lymphocyte counts. CONCLUSION: The prevalence of both anal cytologic abnormalities and anal HPV infection are significantly increased in HIV-seropositive women.

Adult↗
PubMed1996

Low prevalence of human papillomavirus infection of the cervix in renal transplant recipients.

BACKGROUND: An increased risk of anogenital tract malignancies has been noted among renal transplant recipients. A high prevalence of human papillomavirus (HPV) infection of the cervix in the female renal-transplant population has been assumed based on increasing evidence suggesting that HPV infection is the major risk factor for cervical intraepithelial neoplasia (CIN) and cervical cancer. It has been assumed that immunosuppression leads to either a reactivation of latent HPV or a reduction in the host's ability to contain a primary HPV infection, thereby increasing the risk of CIN and cervical cancer. The objective of this study was to evaluate the prevalence of human papillomavirus (HPV) infection in a population of iatrogenically immunosuppressed renal transplant recipients. METHODS: Twenty-one women were recruited from the renal transplant clinic at Presbyterian Hospital and underwent a gynaecological examination which included colposcopy, a Papanicolaou smear, and a cervicovaginal lavage. Lavage samples were analysed for HPV DNA using L1 consensus primers and the polymerase chain reaction (PCR). RESULTS: No cases of cervical intraepithelial neoplasia (CIN) were detected in this cohort of 21 immuno-suppressed renal transplant recipients. HPV DNA was detected in only a single patient. CONCLUSIONS: Our data suggests that HPV infection is not highly prevalent among older, cytologically normal renal transplant recipients, particularly those who are currently monogamous or not presently sexually active. This study suggests that recent sexual behaviours are more important than past behaviours as a determinant of HPV status in transplant recipients, and also suggests that education concerning the avoidance of high-risk sexual behaviour is an important part of the care of the female renal transplant recipient. Our data is consistent with previous work suggesting that the incidence of CIN is declining in transplant recipients, and it also suggests that the prevalence of HPV infection may be declining as well.

Adult↗