Morphological lymphocytic reaction, patient prognosis and PD-1 expression after surgical resection for oesophageal cancer.

BACKGROUND: Immune checkpoint inhibitors, such as antibody against programmed cell death protein (PD-1), have demonstrated antitumour effects in patients with malignancies, including oesophageal cancer. A lymphocytic reaction observed by pathological examination is a manifestation of the host immune response to tumour cells. It was hypothesized that a stronger lymphocytic reaction to tumours might be associated with favourable prognosis in oesophageal cancer. METHODS: Using a database of resected oesophageal cancers, four morphological components of lymphocytic reactions (peritumoral, intranest, lymphoid and stromal) to tumours were evaluated in relation to clinical outcome, PD-1 expression by immunohistochemistry and total lymphocyte count in blood. RESULTS: Resected oesophageal cancer specimens from 436 patients were included in the study. Among the four morphological components, only peritumoral reaction was associated with patient prognosis (multivariable P for trend <0·001); patients with a higher peritumoral reaction had significantly longer overall survival than those with a lower reaction (multivariable hazard ratio 0·48, 95 per cent c.i. 0·34 to 0·67). The prognostic effect of peritumoral reaction was not significantly modified by other clinical variables (all P for interaction >0·050). Peritumoral reaction was associated with total lymphocyte count in the blood (P < 0·001), supporting the relationship between local immune response and systemic immune competence. In addition, higher morphological peritumoral reaction was associated with high PD-1 expression on lymphocytes in tumours (P = 0·034). CONCLUSION: These findings should help to improve risk-adapted therapeutic strategies and help stratify patients in the future clinical setting of immunotherapy for oesophageal cancer.

ANTECEDENTES: Los inhibidores de los puntos de control inmunitario (checkpoints) (p.ej. los anticuerpos anti-PD-1) han demostrado efectos antitumorales en pacientes con tumores malignos, incluido el cáncer de esófago. La reacción linfocítica detectada en estudios anatomopatológicos es una manifestación de la respuesta inmune del huésped a las células tumorales. Se estableció la hipótesis de que una mayor reacción linfocítica a los tumores podría asociarse con un mejor pronóstico en el cáncer de esófago. MÉTODOS: Usando una base de datos de 436 cánceres de esófago resecados, se evaluaron cuatro componentes morfológicos (peritumoral, intra-epitelial, linfoide y estromal) de las reacciones linfocíticas a tumores en relación con los resultados clínicos, la expresión inmunohistoquímica de PD-1 y el recuento total de linfocitos en sangre. RESULTADOS: De los cuatro componentes, solamente la reacción peritumoral se asoció con el pronóstico del paciente (P multivariable para tendencia < 0,001): los pacientes con mayor reacción peritumoral presentaron una supervivencia global significativamente más prolongada que aquellos pacientes con menor reacción peritumoral (cociente de riesgos instantáneos multivariable, hazard ratio, HR: 0,48; i.c. del 95%: 0,34 -0,67; P <0,001). El efecto pronóstico de la reacción peritumoral no se modificó significativamente por otras variables clínicas (todas las P para la interacción > 0,05). La reacción peritumoral se asoció con el recuento total de linfocitos en la sangre (P < 0,001), lo que respalda la relación entre la respuesta inmune local y la competencia inmune sistémica. Además, una elevada reacción morfológica peritumoral se asoció con una alta expresión de PD-1 en linfocitos tumorales (P = 0,034). CONCLUSIÓN: Estos hallazgos deberían ayudar a mejorar las estrategias terapéuticas adaptadas al riesgo y contribuir a estratificar a los pacientes en el entorno clínico futuro de la inmunoterapia para los pacientes con cáncer de esófago.

Clinical utility of exhaled carbon monoxide in assessing preoperative smoking status and risks of postoperative morbidity after esophagectomy.

Whereas smoking constitutes a significant risk factor for postesophagectomy morbidity, there is no reliable method to assess the smoking status of patients prior to the procedure. Since exhaled carbon monoxide (CO) is an indicator of recent smoking, this paper hypothesizes that this is a useful parameter in assessing current smoking status and may help predict morbidity following esophagectomy. Sixty-nine patients, who had undergone elective three-incision esophagectomy with two- or three-field lymphadenectomy for esophageal cancer, were prospectively studied between February 2015 and September 2017. At surgical admission, they were asked about their smoking history, their exhaled CO levels were evaluated, and they were grouped into three based on their CO levels. These were 0 parts per million (ppm), >0 and <7 ppm, and ≥7 ppm. Their postoperative morbidity was also assessed. Approximately 13.5% of the patients showed high levels of exhaled CO ≥ 7 ppm, despite preoperatively reporting smoking cessation for over a month. Morbidities of the Clavien-Dindo classification (CDc) ≥ II increased as exhaled CO levels increased and severe morbidity of CDc ≥ IIIb frequently was observed in patients with exhaled CO levels ≥7 ppm. The logistic regression analysis showed that exhaled CO level ≥7 ppm was an independent risk factor for severe postesophagectomy morbidity. Overall, the results of this study suggest that exhaled CO levels may be useful in estimating current smoking status and that it may also help give an estimation of the risk of postesophagectomy morbidity.

Pyloroplasty may reduce weight loss 1 year after esophagectomy.

Weight loss after esophagectomy is common and is associated with unfavorable prognosis. However, the clinical features and surgical methods that influence postesophagectomy weight loss are not well characterized. This study aims to determine those features (especially the surgical methods) that may affect postoperative weight loss. We reviewed 221 esophageal cancer patients who had undergone esophagectomy at Kumamoto University Hospital (Kumamoto, Japan) between November 2012 and June 2015. Among these, we recruited 106 patients who had undergone transthoracic esophagectomy with gastric conduit reconstruction, had no cancer recurrence within 1 year, and no missing follow-up data. We tabulated the body weight changes and risk factors associated with weight loss exceeding 10% at 1-year postesophagectomy. The mean body weights at baseline and 1-year postsurgery were 60.3 kg (standard error (SE): 0.91) and 52.6 (SE: 0.91), respectively. One year postsurgery, the body weights had changed as follows: mean: -12.2%; median: -12.9%; standard deviation: 9.06; range: -36.1-18.56%; interquartile range: -10.5 to -14.0%. In the multivariate logistic regression analysis, the absence of pyloroplasty was the sole risk factor for more than 10% weight loss (OR: 3.22; 95% CI: 1.08-11.9; P = 0.036). Our data suggest that pyloroplasty with esophagectomy can overcome the post-surgical weight loss.

Minimally invasive esophagectomy may contribute to long-term respiratory function after esophagectomy for esophageal cancer.

Evidence suggests that minimally invasive esophagectomy has several advantages with regard to short-term outcomes, compared to open esophagectomy in esophageal cancer patients. However, the impact of minimally invasive esophagectomy on long-term respiratory function remains unknown. The objective of this study is to assess the association between use of the minimally invasive esophagectomy and long-term respiratory dysfunction in esophageal cancer patients after esophagectomy. This retrospective single institution study using prospectively collected data included 87 consecutive esophageal cancer patients who had undergone esophagectomy. All patients underwent a respiratory function test before, and one year after esophagectomy. Logistic regression analysis was used to compute the hazard ratio for long-term respiratory dysfunction. Minimally invasive esophagectomies were performed in 53 patients, and open esophagectomies in 34 patients. The two groups showed no significant differences in terms of postoperative complications and postoperative course. Nor were any differences observed between the two groups in terms of volume capacity (L) and forced expiratory volume 1.0 (L) before esophagectomy (P > 0.34). However, one year after esophagectomy, the decreases in volume capacity and forced expiratory volume 1.0 were significantly less in the minimally invasive esophagectomy group than in the open esophagectomy group (P = 0.04 and P = 0.007, respectively). Multivariate analyses revealed that minimally invasive esophagectomy was an independent favorable factor for maintenance of forced expiratory volume 1.0 (hazard ratio = 0.17, 95% confidence interval 0.04-0.71; P = 0.01). Minimally invasive esophagectomy may be an independent favorable factor for maintenance of long-term respiratory function in esophageal cancer patients after esophagectomy.

Monitoring sputum culture in resected esophageal cancer patients with preoperative treatment.

Pneumonia is a major cause of postesophagectomy mortality and worsens the long-term survival in resected esophageal cancer patients. Moreover, preoperative treatments such as chemotherapy or chemoradiotherapy (which have recently been applied worldwide) might affect the bacterial flora of the sputum. To investigate the association among preoperative treatments, the bacterial flora of sputum, and the clinical and pathological features in resected esophageal cancer patients, this study newly investigates the effect of preoperative treatments on the bacterial flora of sputum. We investigated the association among preoperative treatments, the bacterial flora of sputum, and clinical and pathological features in 163 resected esophageal cancer patients within a single institution. Pathogenic bacteria such as Candida (14.1%), Staphylococcus aureus (6.7%), Enterobacter cloacae (6.1%), Haemophilus parainfluenzae (4.9%), Klebisiella pneumoniae (3.7%), Methicillin-resistant Staphylococcus aureus (MRSA) (3.7%), Pseudomonas aeruginosa (2.5%), Escherichia coli (1.8%), Streptococcus pneumoniae (1.8%), and Haemophilus influenzae (1.2%) were found in the sputum. The pathogen detection rate in the present study was 34.3% (56/163). In patients with preoperative chemotherapy and chemoradiotherapy, the indigenous Neisseria and Streptococcus species were significantly decreased (P= 0.04 and P= 0.04). However, the detection rates of pathogenic bacteria were not associated with preoperative treatments (all P> 0.07). There was not a significant difference of hospital stay between the sputum-monitored patients and unmonitored patients (35.5 vs. 49.9 days; P= 0.08). Patients undergoing preoperative treatments exhibited a significant decrease of indigenous bacteria, indicating that the treatment altered the bacterial flora of their sputum. This finding needs to be confirmed in large-scale independent studies or well-designed multicenter studies.

Intestinal epithelial culture under an air-liquid interface: a tool for studying human and mouse esophagi.

This study investigated whether an intestinal epithelial culture method can be applied to mouse and human esophageal cultures. The esophagi harvested from 1-day-old mice and adult humans were maintained in collagen gels. A commercially available culture medium for human embryonic stem cells was used for the human esophageal culture. We discovered that the intestinal epithelial culture method can be successfully applied to both mouse and human esophageal cultures. The long-term cultured esophageal organoids were rod-like luminal structures lined with myofibroblasts. We discovered that regeneration of the esophageal mucosal surface can be almost completely achieved in vitro, and the advantage of this method is that organoid cultures may be generated using host-derived fibroblasts as a niche. This method is a promising tool for mouse and human research in intestinal biology, carcinogenesis, and regenerative medicine.

Prognostic and clinical impact of sarcopenia in esophageal squamous cell carcinoma.

Recently, depletion of skeletal muscle mass (sarcopenia) has been linked to poor prognosis in several types of cancers, but has not been investigated in esophageal squamous cell carcinoma (ESCC). This retrospective study investigates the relationship between sarcopenia and clinical outcome in ESCC patients treated by surgical resection or definitive chemoradiation therapy (dCRT). The study was retrospectively conducted in a single academic hospital in Kumamoto, Japan, and involved 325 ESCC patients (256 surgical cases and 69 dCRT cases) treated between April 2005 and April 2011. Skeletal muscle mass was quantified by radiologic measures using standard computed tomography scans. The skeletal muscle tissue in the 325 ESCC patients was distributed as follows: mean: 47.10; median: 46.88; standard deviation (SD): 7.39; range: 31.48-71.11; interquartile range, 46.29-47.90. Skeletal muscle tissue was greater in male patients than in female patients (P < 0.0001), but was independent of other clinical and tumor features. Sarcopenia was not significantly associated with overall survival (log rank P = 0.54). Lymph node involvement significantly altered the relationship between sarcopenia and survival rate (P for interaction = 0.026). Sarcopenia significantly reduced the overall survival of patients without lymph node involvement (log rank P = 0.035), but was uncorrelated with overall survival in patients with lymph involvement (log rank, P = 0.31). The anastomosis leakage rate was significantly higher in the sarcopenia group than in the non-sarcopenia group (P = 0.032), but other surgical complications did not significantly differ between the two groups. Sarcopenia in ESCC patients without lymph node involvement is associated with poor prognosis, indicating sarcopenia as a potential biomarker for identifying patients likely to experience an inferior outcome. Moreover, sarcopenia was associated with anastomosis leakage but no other short-term surgical outcome.

Radiofrequency ablation for pulmonary metastases from esophageal squamous cell carcinoma.

Radiofrequency ablation (RFA) is increasingly being used for the treatment of intrathoracic malignancies. Although RFA has been found to be promising in the treatment of lung metastases from some types of neoplasms, little is known concerning its clinical significance in the treatment of pulmonary metastasis from esophageal squamous cell carcinoma (ESCC). This retrospective study evaluated the feasibility, safety, and effectiveness of computed tomography-guided RFA for pulmonary metastasis from ESCC. A series of 10 ESCC patients with 17 pulmonary tumors were included. Correct placement of the ablation device into the target tumor proved to be feasible in all tumors (100%). The mean visual analog scale score, with values that ranged from 0 (no pain) to 10 (worst pain possible), was 1. This suggested that this procedure was well tolerated. No procedure-related deaths occurred. A pneumothorax needing drainage was a major complication in two patients. Local control of ablated tumor lasting for at least 1 year was achieved in 10 (83%) of 12 assessable tumors. Although locoregional recurrences developed in two tumors, these lesions could be recontrolled by repeat treatment with RFA. Three patients died of recurrent disease. The predicted 1- and 2-year overall survival rates after lung RFA were 77.8% and 62.2%, respectively. Percutaneous computed tomography-guided RFA yielded relatively high levels of local control in patients with pulmonary metastases from ESCC and was associated with an acceptable level of complications. It was concluded that a prospective study will be necessary to evaluate the effectiveness of a combination of systemic therapy and RFA for ESCC lung metastases.

Frequency of HER2 expression of circulating tumour cells in patients with metastatic or recurrent gastrointestinal cancer.

BACKGROUND: The clinical significance of circulating tumour cell (CTC) detection in gastrointestinal (GI) cancer remains controversial and the molecular biological characteristics of CTCs are poorly understood. METHODS: A total of 87 patients with metastatic or recurrent GI cancer were prospectively enrolled. Circulating tumour cells and their HER2 status were assessed using the CellSearch System. RESULTS: Among the 62 CTC-positive cases, we found 22 discordant cases (35.5%). Among the HER2-negative primary tumours, 17 of 54 developed HER2-positive CTCs. Five of eight had HER2-negative CTCs among the HER2-positive primary tumours. CONCLUSION: The findings in the current study suggest that it is critical to evaluate the HER2 status of not only the primary tumour but also the CTCs because the metastasising tumour cells are the primary target of systemic therapy.

Methylation levels of LINE-1 in primary lesion and matched metastatic lesions of colorectal cancer.

BACKGROUND: LINE-1 methylation level is a surrogate marker of global DNA methylation. LINE-1 methylation in primary colorectal cancers (CRCs) is highly variable and strongly associated with a poor prognosis. However, no study has examined LINE-1 methylation levels of metastatic CRCs in relation to prognosis or assessed the heterogeneity of LINE-1 methylation level within the primary CRCs. METHODS: Pyrosequencing was used to quantify LINE-1 methylation level in 42 liver metastases, 26 matched primary tumours, and 6 matched lymph node (LN) metastases. KRAS, BRAF, and PIK3CA mutation status and microsatellite instability (MSI) status were also examined. RESULTS: The distribution of LINE-1 methylation level in liver metastases was as follows: mean, 67.3; range, 37.1-90.1. Primary tumours showed LINE-1 methylation levels similar to those of matched liver and LN metastases. The difference in LINE-1 methylation level between superficial areas and invasive front areas was within 7.0 in all six cases evaluated. Prognostic impact of LINE-1 hypomethylation in liver metastases on overall survival was not observed. The concordance rate was 94% for KRAS, 100% for BRAF, 88% for PIK3CA, and 97% for MSI. CONCLUSION: Alteration of LINE-1 methylation level may occur in early CRC tumorigenesis, and the LINE-1 methylation level is relatively stable during CRC progression.

Upregulation of ERCC1 and DPD expressions after oxaliplatin-based first-line chemotherapy for metastatic colorectal cancer.

BACKGROUND: The updated randomised phase 2/3 FIRIS study demonstrated the noninferiority of IRIS (irinotecan and S-1) to FOLFIRI (irinotecan, folinic acid, and 5-FU) for metastatic colorectal cancer. Meanwhile, in the subset analysis including patients who previously have undergone oxaliplatin-containing chemotherapy, the IRIS group showed longer survival than the FOLFIRI group. However, the molecular mechanism underlying this result is still unknown. METHODS: The National Cancer Institute 60 (NCI60) cell line panel data were utilised to build the hypothesis. A total of 45 irinotecan-naive metastatic colorectal cancer patients who had undergone hepatic resection were included for the validation study. The mRNA expressions of excision repair cross-complementing group 1 (ERCC1), dihydropyrimidine dehydrogenase (DPD), and topoisomerase-1 (TOP1) were evaluated by quantitative RT-PCR. The expressions of ERCC1 and DPD were also evaluated by immunohistochemistry. RESULTS: Sensitivity to oxaliplatin in 60 cell lines was significantly correlated with that of 5-FU. Resistant cells to oxaliplatin showed significantly higher ERCC1 and DPD expression than sensitive cells. In validation study, ERCC1 and DPD but not TOP1 expressions in cancer cells were significantly higher in FOLFOX (oxaliplatin, folinic acid, and 5-FU)-treated patients (N=24) than nontreated patients (N=21). The ERCC1 and DPD protein expressions were also significantly higher in FOLFOX-treated patients. CONCLUSION: The ERCC1 and DPD expression levels at both mRNA and protein levels were significantly higher in patients with oxaliplatin as a first-line chemotherapy than those without oxaliplatin. The IRIS regimens with the DPD inhibitory fluoropyrimidine may show superior activity against DPD-high tumours (e.g., tumours treated with oxaliplatin) compared with FOLFIRI.

RPN2 expression predicts response to docetaxel in oesophageal squamous cell carcinoma.

BACKGROUND: Neoadjuvant chemotherapy - often using docetaxel in various combinatorial regimens - is a standard treatment choice for advanced oesophageal squamous cell carcinoma (ESCC) in Japan. However, no useful markers exist that predict docetaxel's effects on ESCC. Ribophorin II (RPN2) silencing, which reduces glycosylation of P-glycoproteins and decreases membrane localisation, promotes docetaxel-dependent apoptosis. We investigated whether RPN2 expression in ESCC biopsy specimens could be a predictive biomarker in docetaxel-based neoadjuvant chemotherapy. METHODS: We evaluated RPN2 expression immunohistochemically in biopsy specimens from 79 patients with node-positive ESCC, who received docetaxel-based adjuvant chemotherapy, and compared clinical and pathological responses between the RPN2-positive and RPN2-negative groups. We also studied susceptibility of RPN2-suppressed ESCC cells to docetaxel. RESULTS: The RPN2-negative group had better clinical and pathological responses to docetaxel than the RPN2-positive group. We also found RPN2 suppression to alter docetaxel susceptibility in vitro. CONCLUSION: Expression of RPN2 in biopsy specimens could be a useful predictive marker for response to docetaxel-based neoadjuvant chemotherapy in ESCC.

Overexpression of microRNA-223 regulates the ubiquitin ligase FBXW7 in oesophageal squamous cell carcinoma.

BACKGROUND: F-box and WD repeat domain-containing 7 (FBXW7) is a cell cycle regulatory gene whose protein product ubiquitinates positive cell cycle regulators such as c-Myc, cyclin E, and c-Jun, thereby acting as a tumour-suppressor gene. This study focused on microRNA-223 (miR-223), which is a candidate regulator of FBXW7 mRNA. The aim of this study was to clarify the clinical significance of miR-223 and FBXW7 in oesophageal squamous cell carcinoma (ESCC) patients, and to elucidate the mechanism by which FBXW7 is regulated by miR-223. METHODS: The expression levels of miR-223 and the expression of FBXW7 protein was examined using 109 resected specimens to determine the clinicopathological significance. We also investigated the role of miR-223 in the regulation of FBXW7 expression in ESCC cell lines in an in vitro analysis. RESULTS: We found that miR-223 expression was significantly higher in cancerous tissues than in the corresponding normal tissues. There was a significant inverse relationship between the expression levels of miR-223 and FBXW7 protein. Moreover, patients with high miR-223 expression demonstrated a significantly poorer prognosis than those with low expression. On the basis of a series of gain-of-function and loss-of-function studies in vitro, we identified FBXW7 as a functional downstream target of miR-223. CONCLUSION: Our present study indicates that high expression of miR-223 had a significant adverse impact on the survival of ESCC patients through repression of the function of FBXW7.

Bone marrow and peripheral blood expression of ID1 in human gastric carcinoma patients is a bona fide indicator of lymph node and peritoneal metastasis.

Recent studies have showed that the bone marrow-derived endothelial progenitor cells play critical roles in metastasis and that ID1 is required in metastasis as regulator of angiogenesis. Therefore, we investigated the clinical significance of ID1 mRNA expression in bone marrow and peripheral samples in patients with gastric cancer. Two hundred and eighty-nine bone marrow and 196 peripheral blood samples from gastric cancer patients were collected and analysed by quantitative RT-PCR for ID1. The ID1 protein expression in one bone marrow, three metastatic lymph nodes and three peritoneal disseminated tumours was examined by immunohistochemical methods. In both bone marrow and peripheral blood samples, ID1 mRNA expression in the metastatic group was significantly higher than in any other group (P=0.003, P=0.0001, respectively) and significantly associated with lymph node metastasis and peritoneal dissemination. The cells in bone marrow with metastatic cancer stained strongly with ID1 compared with those of healthy volunteers. The expression of ID1 mRNA in bone marrow and peripheral blood was significantly associated with lymph node metastasis and peritoneal dissemination, and therefore constitutes a predictable marker for lymph node metastasis and peritoneal dissemination.

Physicochemical speciation of molybdenum in rain water.

A combination of a sensitive catalytic determination method with filtration and ultrafiltration has been used for the physicochemical speciation of molybdenum in natural and synthetic rain water samples. The concentration (CL) of labile molybdenum was evaluated by a direct catalytic determination. The total concentration (CT ) of molybdenum was determined after the acid decomposition of the sample to calculate the non-labile concentration (CT-CL). From the speciation results, molybdenum species in the successive rainfall sample were found in a fraction with smaller molecular weights < 10(3) Da and characterized as labile forms, i.e. simple molybdate ions. Non-labile molybdenum existed in particulate matter (> or = 0.45 microm in particle size) and distributed predominantly in the initial rainfall sample. The coprecipitation with Fe(III) hydroxide contributed to the formation of the non-labile molybdenum. In the initial rainfall sample, a small part of molybdenum was labile in the particle fraction (> or = 0.45 microm). This type of molybdenum was associated with the formation of humic iron aggregates.

Observations of sudden structural-changes of the faulted-halves of the DAS structure on quenched Si(1 1 1) by STM

We have carried out scanning tunneling microscopy (STM) observations of unreconstructed regions on quenched Si(1 1 1) surfaces at 380 degrees C at a scanning speed of 1.7 s per frame. In the regions, it is found that single faulted-halves of the dimer-adatom-stacking-fault (DAS) structure are formed isolatedly or at the edges of the surrounding DAS domains sharing one corner hole. In such "living" regions, we have succeeded to observe sudden structural changes of the faulted-halves during line scans in single frames of STM images.

Comparative Surface Studies at Atomic Resolution with Ultrahigh Vacuum Variable-Temperature Atomic Force and Scanning Tunneling Microscopes.

: With the ultrahigh vacuum variable-temperature scanning tunneling microscope (UHV-VT-STM), atomic-level observation has been achieved. An ultrahigh vacuum atomic force microscope (UHV-AFM) has also been developed, with success in obtaining atom images where observation in noncontact (NC) mode with a frequency modulation (FM) detection method was attempted. Using the FM detection method in the constant oscillation amplitude of the cantilever excitation mode, we have obtained atomic-resolution images of Si(111) 7 x 7 structures and Si(100) 2 x 1 structures and other structures together with STM images in an ultrahigh vacuum environment. Also shown here are contact potential difference (CPD) images using the NC-AFM method.

Uric acid photo-oxidation assay: in vitro comparison of sunscreening agents.

We present a new method to evaluate the photo-oxidative activity of sunscreening agents based on the photodynamic oxidation of uric acid. Uric acid was selected as the oxidant probe for its high reactivity to singlet oxygen and oxygen radicals, high sensitivity of detection using electrochemical (EC) techniques, low light absorptivity and high photochemical stability in the UVA/B region of interest, and stability to autoxidation. The method is demonstrated by the photodynamic oxidation of uric acid on co-irradiation with Rose Bengal, a highly efficient photosensitizing dye for the production of singlet oxygen (1O2). Using this assay we found that the relative photodynamic oxidation rates of UVB-absorbing sunscreens in 80% methanol on irradiation with >290 nm light decreased in the order 2-ethylhexyl 4-dimethylaminobenzoate (DMABA-2EH) >> 2-ethylhexyl 4-methoxycinnamate (MCA-2EH) and the experimental sunscreens, 1-(1,1-dimethylethyl)-3-octanoyl-4,4-dimethyl- 1,4,5,6,-tetrahydropyridine (ICI-319) and 1-(2-methylpropyl)-3-propionyl-4,4-dimethyl-1,4,5,6-tetrahydropyridine (ICI-855). The relative photodynamic oxidation rates of UVA-absorbing sunscreens decreased in the order 4-tert-butyl-4'-methoxydibenzoylmethane (BMDBM) and 4-(2-propyl)benzophenone (PB) > 2-hydroxy-4'-methoxy-benzophenone (HMB) and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB). We have confirmed the photodynamic activity of DMABA-2EH for the production of singlet oxygen (1O2) using electron paramagnetic resonance (EPR) spectroscopy and the reagent 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP). We failed to detect the photodynamic production of the oxyradicals, superoxide (O2.-) and hydroxyl radical (HO.) using N-tert-butyl-a-phenylnitrone (PBN) and 5,5-dimethyl-1-pyrrolidine-1-oxide (DMPO) as a result of photochemical interference caused by these spin-trapping reagents. The uric acid photo-oxidation assay was also used to compare the photodynamic reactivity of light-reflective, microfine oxides TiO2, ZnO and ZrO2 suspended in aqueous 80% methanol. All of the microfine oxides (uncoated) showed greater photodynamic reactivity in equimolar dispersion than did any of the organic UVA- and UVB-absorbing sunscreens in homogeneous solution. In this assay the photodynamic oxidation rates for the microfine oxides decreased in the order ZnO >> TiO2 (anatase) > ZrO2 > TiO2 (rutile).

Effect of nitric oxide on the ligand-binding activity of albumin.

The redox state of the Cys-34 on albumin plays an important role in ligand binding of this plasma protein. We previously reported that mixed-disulfide formation of albumin with low molecular weight thiols, such as cysteine and glutathione, increased the affinity of this protein for phenolsulfophthalein (PSP) and Cu(II). Although nitric oxide (NO) and its metabolites easily react with various thiols, including that of albumin, and form S-nitrosothiol derivatives, the effect of such modification on the ligand-binding activity of this plasma protein remains to be elucidated. Kinetic analysis revealed that S-nitrosylation of Cys-34 on bovine serum albumin (BSA) decreased its binding activity for PSP. NO also decreased the ligand-binding activity of fresh plasma samples from rat and human. S-nitrosylation also decreased the binding activity of BSA for Cu(II). These results indicate that reversible modification of the Cys-34 by NO and oxidative stress might play regulatory roles in the binding and transport of organic anions and heavy metals in the circulation.