Perceptions of climate change and associated health impacts among communities in Johor River Basin, Malaysia.

INTRODUCTION: As climate change is threatening every region of the world, extreme weather events resultant of global warming is occurring at increasing rate and scale in Malaysia. Weather-related disasters such as flood and haze pose critical challenges to the infrastructure and raise public health concerns in the country, especially when main economic sectors rely heavily on climate variability. Public perception on environmental issues is crucial for development of pro-environmental policies. Among studies conducted to understand public awareness regarding global warming, reports of perception on the health impacts were very limited. Taking this limitation into account, this study was designed to examine the perception on the health impacts of climate change among the diverse communities living in the Johor River Basin. MATERIALS AND METHODS: The cross-sectional study was conducted through cloud-data-based digital questionnaires completed by randomly selected residents in the Johor River Basin (n=647). Data was analysed with descriptive statistics using SPSS 27 (IBM®) Software. Comparisons between indigenous and non-indigenous communities were performed using Chi square analysis. RESULTS: Respondents in this study consisted of indigenous people (n=79) and non-indigenous people (n=568). Indigenous respondents generally perceived more frequent occurrence of extreme weather events in the next 20 years, even for the phenomena unfamiliar in Malaysian settings. All respondents showed similar concerns for health impacts of global warming, although the non-indigenous respondents perceived the risk further into the future (25 years) compared to the indigenous respondents who perceived current or imminent (<10 years) risks. Intense concerns for self, children, family members and community were shown by nearly all indigenous respondents (97-99%), while the non-indigenous people in this study expressed stronger concerns at country level and for future generations. During the last haze episode, most indigenous respondents (85%) did not notice any change in air quality nor discomfort among family members, in contrast 70% of the nonindigenous respondents claimed to have suffered from breathing problems themselves as well as others in the family. All respondents were concerned about air quality in their surroundings, indigenous people were concerned for the near future (<10 years), and non-indigenous people were concerned for the next 25 years. CONCLUSION: In this study, respondents were generally concerned about the health impacts of unimpeded global warming. There was significant difference in perceptions between indigenous and non-indigenous respondents. The findings were useful, complemented with further studies, to improve understanding of public awareness and to help develop relevant education programmes accessible for wider audience.

BCAS2 promotes prostate cancer cells proliferation by enhancing AR mRNA transcription and protein stability.

BACKGROUND: We showed previously that breast carcinoma amplified sequence 2 (BCAS2) functions as a negative regulator of p53. We also found that BCAS2 is a potential AR-associated protein. AR is essential for the growth and survival of prostate carcinoma. Therefore we characterised the correlation between BCAS2 and AR. METHODS: Protein interactions were examined by GST pull-down assay and co-immunoprecipitation. Clinical prostate cancer (PCa) specimens were evaluated by immunohistochemical assay. AR transcriptional activity and LNCaP cell growth were assessed by luciferase assay and MTT assay, respectively. RESULTS: BCAS2 expression was significantly increased in PCa. BCAS2 stabilised AR protein through both hormone-dependent and -independent manners. There are at least two mechanisms for BCAS2-mediated AR protein upregulation: One is p53-dependent. The p53 is suppressed by BCAS2 that results in increasing AR mRNA and protein expression. The other is via p53-independent inhibition of proteasome degradation. As BCAS2 can form a complex with AR and HSP90, it may function with HSP90 to stabilise AR protein from being degraded by proteasome. CONCLUSIONS: In this study, we show that BCAS2 is a novel AR-interacting protein and characterise the correlation between BCAS2 and PCa. Thus we propose that BCAS2 could be a diagnostic marker and therapeutic target for PCa.

Retrospective imaging audit and cost analysis of medical oncology inpatients admitted to Westmead Hospital.

BACKGROUND: Cancer patients often require complex and expensive admissions necessitating multiple investigations. We conducted an audit of cost of imaging performed on medical oncology inpatients in a teaching hospital in New South Wales. AIMS: Our overall aim was to assess cost and appropriateness of imaging studies in inpatients. METHODS: Data were collected on 219 consecutive evaluable inpatients admitted to Westmead Hospital (August-October 2012). A panel of oncology doctors assessed cost and appropriateness of imaging. RESULTS: The total expenditure for the cohort was $106,488.15 over 624 investigations (range: 0-26, median: two per admission). Of this sum, $8881.91 (8%) was deemed inappropriate. The most frequently ordered test was chest X-ray (251). Imaging cost per admission was $0-2478 (range), $324.95 (median), $486.99 (mean). Cost trended to increase with age of patient ($186.40 (18-40), $477.22 (41-65), $489.50 (66-75), $575.33 (>75) ). Mean cost was higher for patients treated with palliative ($493.98) vs curative ($307.59) intent. Mean cost was higher for patients consulted by palliative care and other subspecialties. There was variation of average cost by discharge destination - other hospital ($262.23), palliative care unit ($334.08), home ($480.84) and death ($769.93). Although imaging ordered was deemed overwhelmingly clinically appropriate, approximately $35,000/year is spent on inappropriate tests, mostly due to duplication or scans that could have been performed as an outpatient. CONCLUSION: Our audit supports that the current spending patterns on imaging within our department is predominantly appropriate and necessary. Duplication and expenditure may be reduced by improving electronic access from the ward to outpatient scan results.

Trends in Clinical Breast Density Assessment From the Breast Cancer Surveillance Consortium.

Changes to mammography practice, including revised Breast Imaging Reporting and Data System (BI-RADS) density classification guidelines and implementation of digital breast tomosynthesis (DBT), may impact clinical breast density assessment. We investigated temporal trends in clinical breast density assessment among 2 990 291 digital mammography (DM) screens and 221 063 DBT screens interpreted by 722 radiologists from 144 facilities in the Breast Cancer Surveillance Consortium. After age-standardization, 46.3% (95% CI = 44.1% to 48.6%) of DM screens were assessed as dense (heterogeneously/extremely dense) during the BI-RADS 4th edition era (2005-2013), compared to 46.5% (95% CI = 43.8% to 49.1%) during the 5th edition era (2014-2016) (P = .93 from two-sided generalized score test). Among DBT screens in the BI-RADS 5th edition era, 45.8% (95% CI = 42.0% to 49.7%) were assessed as dense (P = .77 from two-sided generalized score test) compared to 46.5% (95% CI = 43.8% to 49.1%) dense on DM in BI-RADS 5th edition era. Results were similar when examining all four density categories and age subgroups. Clinicians, researchers, and policymakers may reasonably expect stable density distributions across screened populations despite changes to the BI-RADS guidelines and implementation of DBT.

Use of human prostate-specific antigen in monitoring prostate cancer.

The newly reported human prostate-specific antigen (PA) is a specific histiotypic product of human prostate. With the use of a sensitive enzyme immunoassay, the circulating PA in prostatic cancer patients has been evaluated clinically. In 96 patients with advanced stage of disease (D2) and receiving chemotherapies, the pretreatment serum PA levels were found to be of prognostic value with regard to the patient survival. Ten patients with metastatic prostate cancer were monitored for more than 32 weeks by 183 serial PA values and were found generally to respond to the treatment. Additionally, in another group of 32 patients who underwent curative therapies for localized prostate cancer, 161 serum samples were evaluated during periods of 12 to 114 weeks (average 56 weeks). Of these patients, five developed metastases during follow-up, and all were shown to exhibit increasingly elevated PA values, either corresponding to or preceding the clinical diagnosis of disease recurrence. These results suggest that PA is a new marker with potential value to merit further clinical study.

Heavy metal removal from aqueous solution in sequential fluidized-bed reactors.

In this study, the sequential fluidized bed reactors (FBRs), were used to remove heavy metals including, Cu, Pb, and Ni, from synthetic wastewater. Heavy metals were removed through crystallization of metal carbonate and hydroxide precipitates on the surface of sand grains. The results showed that the influent metal concentration limits in the sequential FBRs were higher than those in the vertical FBRs. The removal efficiency for Cu, Pb, and Ni reached 96%, 93%, and 98% when the influent concentrations were 250 mg l(-1), 130 mg l(-1) and 130 mg l(-1), respectively. The pH value in the effluent of the FBR ranged from 8.7 to 9.1. The amount of metal coated onto the sand surface was determined and it was found that most of the metal ions were collected in the first reactor. The mechanism of heavy metal removal in the sequential FBRs concluded crystallization and filtration.

Differential sensitivity to hydroxyl radicals of pre- and postjunctional neurovascular transmission in the isolated canine mesenteric vein.

In some pathophysiological conditions, the first target of reactive oxygen intermediates is the vascular system. Superoxide anions, when generated in the vascular circulation, may then escape into the extracellular space via an anion channel and, following dismutation to hydrogen peroxide (H(2)O(2)), form hydroxyl radicals (HO(*)). In an attempt to understand the role of HO(*) in the regulation of transmission at the sympathetic neurovascular junction, the effect of HO(*) at nerve terminals was examined by measuring the amount of noradrenaline (NA) released from isolated, spirally cut, superfused canine mesenteric vein during basal and electrical stimulation (ES; 5Hz, 2ms, 9V); tension development evoked by ES was also recorded simultaneously. HO(*) was generated from Fenton's reagent (1. 5x10(-4)M H(2)O(2) plus 10(-4)M FeSO(4)); generation of HO(*) from H(2)O(2)/FeSO(4) in the superfusate was monitored by electron spin resonance spectroscopy using the spin-trap 5, 5-dimethyl-1-pyrroline-N-oxide throughout the experimental time course. Exposure to HO(*) of the helical strips produced an irreversible decrease in tension development evoked by ES with no effect on NA release, suggesting that the observed effect is elicited postjunctionally. The susceptibility of the processes of NA-mediated contraction to HO(*) may differ greatly from that of the NA release mechanism at the prejunctional site. Exposure of the strip preparation to HO(*) leads to a substantial stimulation of basal release of NA without affecting ES-evoked NA release, possibly due to enhanced non-exocytotic Ca(2+)-independent release elicited by HO(*). A direct demonstration of this concept was obtained by showing a significant increase in the basal response of NA release in Ca(2+)-free solution. The major conclusion of the present study is that HO(*) can damage NA-mediated contraction of the vascular preparations at the postjunctional site, and may selectively induce a non-exocytotic release of NA from the prejunctional site of sympathetic neurotransmission.

Combined pre-operative chemotherapy with intra-arterial cisplatin and continuous intravenous adriamycin for high grade osteosarcoma.

Osteosarcoma is one of the most common juvenile malignant tumors in Korea. Combined modality treatment (pre-operative chemotherapy + limb salvage surgery + adjuvant therapy) improved the patients' overall survival and quality of life. We evaluated the efficacy and feasibility of pre-operative chemotherapy with intra-arterial (IA) cisplatin plus continuous intravenous infusion (CI) of adriamycin. We assessed the rate of limb salvage, recurrence pattern and the survival impact based on the histologic response of pre-operative chemotherapy. Fourty-one patients with histologically-proven high grade osteosarcoma of the extremities were enrolled from January 1990 to June 1995. Pre-operative chemotherapy, cisplatin 120 mg/m2 IA and adriamycin 75 mg/m2/72 h CI was administered every 3 weeks for 3 cycles, followed by limb salvage surgery if possible or by amputation. According to the histologic tumor response, if the tumor necrosis was >90%, the same regimen was administered for 3 cycles as an adjuvant therapy. A salvage regimen (Ifosfamide 7.5 gm/m2/5 d IV + high dose MTX 10 gm/m2 IV+VP-16 360 mg/m2/3 d IV) was administered every 3 weeks for 6 cycles if the tumor necrosis was <90%. Of 41 patients, 37 patients were evaluable for efficacy and toxicities, because 4 patients refused chemotherapy after 1 or 2 cycles. Twenty-one patients were male and 16 were female with median age of 16 years (range 8-41). The tumor locations were: distal femur 20, proximal tibia 8, humerus 6, distal tibia 2 and 1 in proximal femur. All but one patient, who died of neutropenic sepsis, completed the planned pre-operative therapy. Of the 36 patients who received surgery, limb salvage surgery was possible in 30 patients (83.3%) and 27 patients (75%) showed a good response (grade III 10; 27.8%, grade IV 17; 47.2%). With a median follow-up of 23 months, 3-year disease-free survival rate was 54.7% and overall survival rate was 78.3%. Of the 15 patients who recurred, the major metastatic site was the lung. No operation-related mortality was observed. Most patients experienced grade III-IV nausea, vomiting and hematologic toxicities, which were reversible with supportive cares. Pre-operative chemotherapy with IA DDP+CI ADR followed by surgery showed 75% histologic tumor response rate, 83% limb salvage rate and 54.7% 3-year disease-free survival rate with tolerable side effects. To improve the survival rate, the possible role of good salvage chemotherapy with a non-cross resistance regimen in poor responders should be evaluated.

Phase I clinical trial: pharmacokinetics of a novel anthracycline, DA-125 and metabolites. Single dose study.

Single dose of DA-125, 20 (n = 3), 40 (n = 3), 60 (n = 3), 80 (n = 6), or 100 (n = 6) mg/m2 body surface area, was administered intravenously in 5 min to 21 patients with various types of cancer as phase I clinical trial. The main side-effects of DA-125 were nausea, vomiting, leukopenia (especially neutropenia), and thrombocytopenia. Among those, hematological side-effects increased with increased doses of DA-125. No patient developed side-effects equal to or higher than grade III up to DA-125 dose of 60 mg/m2. However, at DA-125 dose of 80 mg/m2, 1 out of 3 patients developed grade III leukopenia and grade IV neutropenia. Therefore, 3 additional patients participated taking the dose of 80 mg/m2; no patient developed side-effects equal to or higher than grade III. Hence, DA-125 dose increased to 100 mg/m2. At DA-125 dose of 100 mg/m2, 2 out of 3 patients developed side-effects equal to or higher than grade III and, therefore, 3 additional patients participated taking this dose. Among the 3 additional patients, 1 patient developed both grade III leukopenia and neutropenia. Therefore, further accrual was stopped at this dose (100 mg/m2). The maximally tolerated dose (MTD) of DA-125 was determined to be 100 mg/m2, and the dose-limiting factor for DA-125 was bone marrow suppression. DA-125 dose of 80 mg/m2, 80% of MTD of DA-125, was recommended as the dose for phase II clinical trial. Cardiotoxicity was not observed in any of the 21 patients according to the ECG and RVG. Neither fever, stomatitis, diarrhea, and renal and nervous system toxicity, nor abnormality in blood coagulation was observed in any of the patients, and death or life-threatening side-effects due to DA-125 were also not observed. Antitumor effects of DA-125 were evaluated from the 21 patients; 6 progressive disease, 14 stable disease, and 1 partial response. Pharmacokinetic parameters of M1, such as AUC, t1/2, CL, VSS, and MRT, seemed to be independent of i.v. doses of DA- 125, 20-100 mg/m2 and less than 0.75% of M1 were excreted in 96 h urine when expressed in terms of DA-125 i.v. dose. M2 was the main metabolite of DA-125 among M1-M4 excreted in urine; 10.1 approximately 22.3% of M2 was excreted in 96 h urine when expressed in terms of DA-125 i.v. dose. Bile was collected via the T-tube in 1 additional patient at the dose of 100 mg/m2. Biliary excretion of M1 and M2 was negligible; less than 0.320 and 4.76% of M1 and M2, respectively, were excreted in 96 h bile when expressed in terms of DA-125 i.v. dose.

[Clinical and cellular biologic diagnosis of Cockayne syndrome: a case report].

We report a case of Cockayne syndrome. A 6-year-old boy presented with a progeroid face, dwarfism, psychomotor retardation, skin photosensitivity and retinal pigmented degeneration. Neurological study disclosed slowed nerve conduction velocities and a brain CT showed calcification in the basal ganglia. Auditory brain stem evoked potential showed prolonged interpeak latency of wave I to wave V. Laboratory evaluation revealed mild liver dysfunction and peripheral eosinophilia. Fibroblast cultures from the patient and his family were exposed to ultraviolet (UV) light of 254 nm, ranging from 1 to 10 J/m2. Under 1 J/m2 irradiation, the surviving fraction of the fibroblasts from the patient, his mother, and a control subject were 40%, 50%, 90% respectively. If the fibroblasts of these subjects were exposed to 2 J/m2 and 3 J/m2 irradiation, the surviving fraction changed to 10%, 22%, 80% and 1.5%, 9%, 68%, respectively. However, fibroblasts from his sister and father showed the same surviving fraction as the control. The study showed that fibroblasts from the patient and his mother were extremely sensitive to UV light irradiation. We also study the concentration of the pyrimidine dimer of DNA in the patient and the control subject. Pyrimidine dimer showed no difference between the patient and the normal subject before and after 24-hour UV irradiation. These results suggest that the sensitivity to UV of Cockayne fibroblasts may be due to a ligase deficiency or to a replicon initiation disturbance in Cockayne cells.

BMP receptor-integrin interaction mediates responses of vascular endothelial Smad1/5 and proliferation to disturbed flow.

BACKGROUND: Vascular endothelial cells (ECs) are constantly exposed to blood flow-induced shear stress. Our previous study demonstrated that disturbed flow with low and oscillatory shear stress (OSS) induces bone morphogenetic protein receptor (BMPR)-specific Smad1/5 activation in ECs, but the underlying mechanisms and the in vivo functional role of Smad1/5 remain unclear. OBJECTIVES: Here we elucidated the molecular mechanisms by which OSS activates EC Smad1/5 and its in vivo functional role. METHODS: Lentiviral Smad5-specific short hairpin RNA (Lenti-shSmad5) was constructed and intra-arterially injected into the lumen of stenosed abdominal aorta in bromodeoxyuridine-infused rats. Co-immunoprecipitation and in situ proximity ligation assays were performed on ECs exposed to OSS (0.5 ± 4 dynes/cm(2) ) in a parallel-plate flow chamber to investigate BMPR-integrin interactions and their regulatory role in OSS-activation of EC Smad1/5. RESULTS: Intra-arterial administration of Lenti-shSmad5 inhibited bromodeoxyuridine uptake of ECs at post-stenotic sites, where disturbed flow with OSS occurs. OSS induced sustained BMPRIB-αv ß3 integrin association in ECs, which was mediated by the intracytoplasmic kinase domain of BMPRII and subsequently activated the Shc/focal adhesion kinase (FAK)/extracellular signal-regulated kinase (ERK) cascade, leading to Smad1/5 activation. This OSS-activation of Smad1/5 induced its association with and activation of runt-related transcription factor-2 (Runx2), leading to activations of mammalian target of rapamycin (mTOR) and p70S6 kinase (p70S6K), a pathway critical for EC proliferation in response to OSS. CONCLUSIONS: Oscillatory shear stress induces synergistic interactions between specific BMPRs and integrin to activate Smad1/5 through the Shc/FAK/ERK pathway, which leads to the activation of the Runx2/mTOR/p70S6K pathway to promote EC proliferation.

Internally displaced human resources for health: villager health worker partnerships to scale up a malaria control programme in active conflict areas of eastern Burma.

Approaches to expand malaria control interventions in areas of active conflict are urgently needed. Despite international agreement regarding the imperative to control malaria in eastern Burma, there are currently no large-scale international malaria programmes operating in areas of active conflict. A local ethnic health department demonstrated that village health workers are capable of implementing malaria control interventions among internally displaced persons (IDPs). This paper describes how these internally displaced villagers facilitated rapid expansion of the programme. Clinic health workers received training in malaria diagnosis and treatment, vector control and education at training sites along the border. After returning to programme areas inside Burma, they trained villagers to perform an increasingly comprehensive set of interventions. This iterative training strategy to increase human resources for health permitted the programme to expand from 3000 IDPs in 2003 to nearly 40,000 in 2008. It was concluded that IDPs are capable of delivering essential malaria control interventions in areas of active conflict in eastern Burma. In addition, health workers in this area have the capacity to train community members to take on implementation of such interventions. This iterative strategy may provide a model to improve access to care in this population and in other conflict settings.

Multi-level partnerships to promote health services among internally displaced in eastern Burma.

Ethnic populations in eastern Burma are the target of military policies that result in forced labour, destruction of food supplies, and massive forced displacement. Despite international assistance to Burmese refugees along the Thai-Burma border, traditional humanitarian models have failed to reach these internally displaced persons (IDPs) within Burma. Nevertheless, through the cultivation of a model (cross border local-global partnerships) 300,000 IDPs in eastern Burma now receive critical health services where, otherwise, there would be none. We describe key elements of the partnership model's genesis in eastern Burma. The role of the local partner, Backpack Health Worker Team (BPHWT), is highlighted for its indigenous access to the IDP populations and its maintenance of programmatic autonomy. These local elements are potentiated by international support for technical assistance, training, resources, and advocacy. International policy and investment should prioritize support of locally-driven health initiatives that utilize local-global partnerships to reach not only IDPs but also other war-torn or traditionally inaccessible populations worldwide.

HIV-1-derived lentiviral vectors and fetal route of administration on transgene biodistribution and expression in rhesus monkeys.

The gene transfer efficiency of lentiviral vectors pseudotyped with vesicular stomatitis virus-glycoprotein (VSV-G) driven by the MND or CMV promoters and expressing the enhanced green fluorescent protein (EGFP) was investigated in fetal rhesus monkeys (Macaca mulatta) (N=21). Fetuses (50+/-10 days gestation; term 165+/-10 days) were injected under ultrasound guidance using an intraperitoneal (i.p.) or intrahepatic (i.h.) approach with a range of 1 x 10(7)-2 x 10(8) infectious particles/fetus. Analysis of transgene biodistribution and expression was performed in multiple tissues at 3-7 months postgene delivery using quantitative techniques. Overall, results indicated the following: (1) i.p. gene transfer at 40 days gestation resulted in a more diffuse distribution of the vector compared to administration at 60 days gestation; (2) vector biodistribution was similar after administration by the i.p. or i.h. routes; and (3) gene expression analysis in transduced tissues showed the presence of mRNA transcripts that correlated with the level of gene transfer. These studies suggest that fetal gene transfer using the i.p. and i.h. routes results in prolonged transduction and expression of the transgene in multiple tissues.

Evolutionary conservation of chloroplast genes coding for the large subunits of fraction 1 protein.

Crystalline fraction 1 protein, obtained from four species of Nicotiana, have identical polypeptide compositions and isoelectric points. However, the tryptic peptide map of the large subunit of this protein from N. knightiana and N. paniculata differs from that of N. tomentosa and N. tomentosiformis. Since the large subunits of fraction 1 protein are coded by chloroplast DNA, the difference in their primary structure reflects the structural changes of the chloroplast genes containing the coding information. This indicates that the rate of mutation of chloroplast DNA seems to be higher than predicated from the analysis of isoelectric points of this protein.

Regulation of xanthine oxidase by nitric oxide and peroxynitrite.

Xanthine oxidase (XO) is a central mechanism of oxidative injury as occurs following ischemia. During the early period of reperfusion, both nitric oxide (NO(*)) and superoxide (O-*(2)) generation are increased leading to the formation of peroxynitrite (ONOO(-)); however, questions remain regarding the presence and nature of the interactions of NO(*) or ONOO(-) with XO and the role of this process in regulating oxidant generation. Therefore, we determined the dose-dependent effects of NO(*) and ONOO(-) on the O-*(2) generation and enzyme activity of XO, respectively, by EPR spin trapping of O-*(2) using 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide and spectrophotometric assay. ONOO(-) markedly inhibited both O-*(2) generation and XO activity in dose-dependent manner, while NO(*) from NO(*) gas in concentrations up to 200 microM had no effect. Furthermore, we observed that NO(*) donors such as NOR-1 also inhibited O-*(2) generation and XO activity; however, these effects were O-*(2)-dependent and blocked by superoxide dismutase or ONOO(-) scavengers. Finally, we found that ONOO(-) totally abolished the Mo(V) EPR spectrum. These changes were irreversible, suggesting oxidative disruption of the critical molybdenum center of the catalytic site. Thus, ONOO(-) formed in biological systems can feedback and down-regulate XO activity and O-*(2) generation, which in turn may serve to limit further ONOO(-) formation.

Skeletal sarcoplasmic reticulum dysfunction induced by reactive oxygen intermediates derived from photoactivated rose bengal.

We investigated the role of reactive oxygen intermediates generated from photoactivation of xanthene dye rose bengal on skeletal sarcoplasmic reticulum (SR) function, which plays a major role in the regulation of intracellular Ca++ and thereby in the generation of force. We used SR microsomes of canine masseter muscle as a model system in which to explore the effect of oxidation by determining oxalate-supported Ca++ uptake, Ca++, Mg++-adenosine triphosphatase (Ca++-ATPase) activity and Ca++ permeability of the SR vesicles. Skeletal SR vesicles exposed to rose bengal (50 nM) illuminated at 560 nm resulted in significant inhibition of Ca++ uptake velocity and Ca++-ATPase activity and in stimulation of Ca++ permeability. The observed effect afforded by illuminated rose bengal was dependent on intensity of light. Most reactive oxygen species scavengers tested had no protective effect; histidine (a powerful quenching agent for singlet oxygen), however, significantly protected the effect of illuminated rose bengal on Ca++ uptake velocity and Ca++-ATPase activity. The illumination of rose bengal also caused histidine-inhibitable loss of total sulfhydryl groups of SR. The increased Ca++ permeability elicited by illuminated rose bengal was blunted by a cocktail of histidine-catalase, but not by histidine alone. Generation of reactive oxygen species (singlet oxygen, superoxide and hydroxyl radical) from photoactivation of rose bengal was studied by electron spin resonance spectroscopy by use of the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP). We found that illumination of rose bengal formed a 1:2:2:1 quartet, characteristic of the hydroxyl radical-DMPO spin adduct, which was effectively blunted by hydroxyl radical scavenger, dimethyl sulfoxide, and by superoxide scavenger, superoxide dismutase. The results of electron spin resonance study also showed that singlet oxygen was produced by photoactivation of rose bengal was detected as singlet oxygen-TEMP product (TEMPO); 2,2,6,6-tetramethylpiperidine-N-oxyl). The formation of TEMPO signal was strongly inhibited by histidine. Similarly, we could detect hydrogen peroxide production from illuminated rose bengal. It is suggested that photoactivation of rose bengal generated singlet oxygen, superoxide, hydrogen peroxide and hydroxyl radical, and the data obtained from the present study indicate that singlet oxygen, rather than superoxide, hydrogen peroxide and hydroxyl radical, to be the active agent in the Ca++ transport system of SR; the observed effect of singlet oxygen may be due to sulfhydryl group oxidation. Our results are also consistent with the view that singlet oxygen does not appear to be an exclusive species that increases Ca++ permeability of SR vesicles, but the increased Ca++ permeability may be caused in part by hydrogen peroxide as well as singlet oxygen.

Inhibition of skeletal sarcoplasmic reticulum Ca2+-ATPase activity by deferoxamine nitroxide free radical.

Deferoxamine is an inhibitor of iron-dependent free radical reactions. Despite the antioxidant roles, prolonged clinical use of the chelator is far from benign, and paradoxically, deferoxamine has been shown to promote lipid peroxidation. The possible toxicity of the drug's metabolites, such as deferoxamine nitroxide free radical, deserves attention. We, therefore, tested the hypothesis that deferoxamine nitroxide radicals produced as a result of enzymatic one-electron oxidation of deferoxamine by horseradish peroxidase in the presence of H2O2 are capable of inactivating Ca2+-ATPase of skeletal sarcoplasmic reticulum microsomes as a model system with which to explore the effect of the radical on a biological membrane. Ca2+-ATPase activity of sarcoplasmic reticulum was depressed by exposure to Fenton's reagent (H2O2/FeSO4); the observed effect was significantly enhanced by deferoxamine. We found that the Fenton reaction produced hydroxyl radical, as determined by electron spin resonance spectroscopy. The formation of hydroxyl radical was completely inhibited by deferoxamine; instead, under the same experimental conditions (in the presence of sarcoplasmic reticulum vesicles with or without FeSO4 but without spin trap 5, 5-dimethyl-1-pyrroline N-oxide), the spectral shape and hyperfine coupling constants of electron spin resonance signals confirmed to be long-lived deferoxamine radical were obtained. Furthermore, exposure of sarcoplasmic reticulum vesicles to deferoxamine radical formed by horseradish peroxidase via reaction with H2O2 caused an inhibition of the Ca2+-ATPase activity. The findings show that the sarcoplasmic reticulum vesicles can act as peroxidases and suggest that deferoxamine enhances the decreased Ca2+-ATPase activity afforded by H2O2/FeSO4 due to formation of its metabolites, possibly deferoxamine nitroxide free radical.

Nonparametric estimation of bounded survival functions with censored observations.

Stochastic ordering of survival functions is a useful concept in many areas of statistics, especially in nonparametric and order restricted inferences. In this paper we introduce an algorithm to compute maximum likelihood estimates of survival functions where both upper and lower bounds are given. The algorithm allows censored survival data. In a simulation study, we found that the proposed estimates are more efficient than the unrestricted Kaplan-Meier product limit estimates both with and without censored observations.