Biomedical subjects
Publications and source records attributed to R Ma.
Explore the source record for details and available documents.
OBJECTIVE: We sought to evaluate the effects of breviscapine to ameliorate graft ischemia-reperfusion (I/R) injury in a rat small bowel transplantation model. METHODS: Thirty-six recipients were randomly divided into three groups (n = 12): operative controls, in which grafts were implanted immediately after harvesting; an I/R control group with grafts preserved in cold lactated Ringer's solution at 4 degrees C for 4 hours before transplantation; and a breviscapine group wherein the graft was treated in the same way as the I/R control group but breviscapine (25 mg/kg/d) was injected intraperitoneally into both the donors and the recipients for 3 days before the operation of and into the recipients after transplantation. We compared the pathological scores for I/R injury, apoptosis index, and content of malondialdehyde (MDA) in the graft. RESULTS: Breviscapine diminished the pathological change caused by I/R injury (breviscapine vs I/R control on 24 hours after operation, 1.50 +/- 0.55 vs 2.17 +/- 0.75; P < .05), decreased the apoptotic index (breviscapine vs I/R control at 24 hours after operation, 27.33 +/- 0.167 vs 73.83 +/- 0.077; P < .05), and reduced the graft tissue content of MDA (breviscapine vs I/R control on 24 hours after operation, 1.717 +/- 0.131 vs 3.167 +/- 0.196; P < .05). CONCLUSIONS: Breviscapine may protect the transplanted small intestine against I/R injury during transplantation in rats.
BACKGROUND: The role of nickel in causing hand dermatitis in some occupations has been difficult to assess due to problems with reliable measurement of the exposure to nickel in the workplace and lack of a definitive threshold for nickel allergic contact dermatitis. It is not uncommon to find nickel allergy on patch testing but it is difficult to determine whether this is of relevance to occupational nickel exposure or simply a reflection of past exposure to nickel-plated jewellery or other nonoccupational nickel exposure. OBJECTIVES: To devise a simple and reproducible method to quantify the amount of nickel on the skin and to apply the technique to measure dermal nickel exposure in various occupational settings. METHODS: A rapid and simple sampling procedure was developed for determination of nickel on the skin of workers potentially exposed to nickel by exposing individuals to nickel-releasing coins and measuring exposure by immersing the exposed thumbs and index fingers directly into graduated sample tubes containing ultrapure water and aqueous nickel extracts. The solutions were analysed by inductively coupled plasma-optical emission spectrometry after stabilization with nitric acid. The method shows advantages over alternatives such as wipe testing and tape stripping in terms of extraction efficiency, speed and ease of operation in the field. A pilot survey of dermal nickel exposure for workers in several occupational settings was conducted. RESULTS: The study suggested that a 'normal' level of nickel on the skin is <10 ng cm(-2). Coin handling induced an appreciable increase in the amount of nickel on the skin within 2 min. Experiments indicated a linear relationship between coin handling (exposure time) and measured dermal nickel levels following standardized coin handling. A pilot survey, conducted among cashiers, shop assistants, bar staff, hairdressers and workers in the nickel industry revealed dermal nickel concentrations ranging from <0.9 to 7160 ng cm(-2). The levels of nickel on the skin of cashiers, shop assistants, bar staff and hairdressers were below the threshold level for water-soluble ionic nickel for occluded exposure at which 10% of nickel-allergic subjects react (0.01% or 100 parts per million, equivalent to 530 ng cm(-2)) and the five-times higher threshold for unoccluded exposure (500 parts per million). The levels in some nickel platers and nickel refinery workers approached or exceeded these levels. However, few cases of nickel dermatitis are observed in plating and refinery facilities, perhaps due to immune tolerance, self-selection or, for refinery workers, exposure to water-insoluble rather than water-soluble nickel compounds. The elicitation threshold for water-soluble nickel compounds cannot be compared directly with dermal exposure to water-insoluble nickel compounds as the latter release a significantly lesser amount of nickel ions. CONCLUSIONS: We describe a reproducible, simple and rapid procedure for the assessment of nickel levels in occupationally exposed individuals.
BACKGROUND: We sought to review 450 rat small bowel transplantation (SBT) operations having a modified microsurgical technique to discuss the key steps for a successful operation. METHODS: Four hundred fifty rat heterotopic small bowel transplantations were performed in 3 stages: the first 80 cases were a training stage, the following 330 cases were for formal experiments, and, in the last stage, 40 cases were to analyze the relationship between the duration of cold preservation and recipient mortality. For all cases, revascularization of the graft was accomplished by an end-to-side anastomosis between the donor superior mesenteric artery or aorta and the recipient infra-renal aorta, and cuffed end-to-end anastomosis between the donor portal vein and the left renal vein of the recipient. The duration of each operation, graft warm ischemia time, and recipient survival rate were compared. RESULTS: In the first stage, the graft warm ischemia time was about 90 minutes where as it was only 35 minutes in the second stage. The longterm survival rates (>5 days) of recipients were 8.8% and 97.3%, respectively. In the 3rd stage, long cold preservation period significantly increased recipient mortality. CONCLUSIONS: Graft warm ischemia time was a key issue associated with recipient mortality; a well-trained, simplified microsurgical anastomosis between graft superior mesenteric artery and recipient aorta accomplished in a shorter time rendered intravenous transfusion not essential for the recipient.
BACKGROUND: The graft protective effect of ulinastatin (UTI) against ischemia-reperfusion injury in small bowel transplantation (SBT) was verified with a rat SBT model. This study was carried out to investigate the effects of UTI on the accumulation and adhesion of neutrophils. METHODS: Twenty-four recipients of rat SBTs were randomly divided into a control group and a UTI group. UTI was injected intravenously into the donor (before harvest of the graft) and into the recipient (50,000 U/kg/d). Variables included graft pathological score; myeloperoxidase content (MPO); expression of intercellular adhesion molecule-1 (ICAM-1) in the graft and plasma concentration of tumor necrosis factor (TNF) in the recipient. RESULTS: The pathological changes of control group grafts were more significant than those of the UTI group. The content of MPO and expression of ICAM-1 in transplanted small intestines were lower among the UTI group as were plasma concentrations of TNF. CONCLUSIONS: UTI may ameliorate graft ischemia-reperfusion injury in SBT through decreasing accumulation and adhesion of neutrophils.
A method for somatic embryogenesis and fertile green plant regeneration from suspension cell-derived protoplasts of rye (Secale cereale L. cv. Auvinen) was developed. Fast-growing and friable embryogenic calli with a high regeneration capacity were induced from immature rye inflorescences using modified MS medium. These friable embryogenic calli were used for suspension culture initiation in liquid AA medium. A high yield of protoplasts was obtained from suspension cell clumps after 3-5 days of subculture. Isolated protoplasts were cultured in KM8p medium. The frequency of protoplast cell divisions and colony formations in liquid culture medium were similar to those on agarose-solidified medium. Compact embryogenic calli were developed from protoplast-derived microcalli in growth medium mMS. Approximately 7% of the transferred embryogenic calli produced green shoots on N6 regeneration medium. Of 33 green plants, 28 were fertile with normal flowering and seed set. The ratio of green and albino plantlets was 1:4. Rye protoplast-derived green plants showed normal diploid characters as determined by flow cytometer analysis and chromosome counting.
INTRODUCTION: Oversecretion of ACTH from pituitary adenomas is associated with morbidity and reduced life expectancies. We hypothesized that radiosurgical treatment may provide effective tumour and hormonal control associated with minimal pituitary insufficiency. METHOD: Data of five patients who underwent LINAC radiosurgery for recurrent or residual Cushing's disease between 1999 and 2002 were prospectively collected. RESULT: Follow-up period ranged from 27 to 49 months (mean 38 months). All patients attained remission in 6-18 months (mean 8.4 months). One patient (20 %) developed biochemical recurrence 12 months after remission. One patient (20 %) developed hydrocortisone deficiency 24 months after radiosurgery. None of the patients had new visual field defect detected on follow-up. CONCLUSION: In this small case series, LINAC radiosurgery was shown to be an effective and safe treatment of persistent or recurrent Cushing's disease following transsphenoidal surgery. Long-term follow-up and larger patient series is recommended for further clarification.
Traffic is the main source of platinum-group element (PGE) contamination in populated urban areas. There is increasing concern about the hazardous effects of these new pollutants for people and for other living organisms in these areas. Airborne and road dusts, as well as tree bark and grass samples were collected at locations in the European cities of Göteborg (Sweden), Madrid (Spain), Rome (Italy), Munich (Germany), Sheffield and London (UK). Today, in spite of the large number of parameters that can influence the airborne PGE content, the results obtained so far indicate significantly higher PGE levels at traffic sites compared with the rural or non-polluted zones that have been investigated (background levels). The average Pt content in airborne particles found in downtown Madrid, Göteborg and Rome is in the range 7.3-13.1 pg m(-3). The ring roads of these cities have values in the range 4.1-17.7 pg m(-3). In Munich, a lower Pt content was found in airborne particles (4.1 pg m(-3)). The same tendency has been noted for downtown Rh, with contents in the range 2.2-2.8 pg m(-3), and in the range 0.8-3.0 and 0.3 pg m(-3) for motorway margins in Munich. The combined results obtained using a wide-range airborne classifier (WRAC) collector and a PM-10 or virtual impactor show that Pt is associated with particles for a wide range of diameters. The smaller the particle size, the lower the Pt concentration. However, in particles <PM-10, some of the highest values correspond to the fraction <0.39 microm. Considering an average Pt content in all particles of approximately 15 pg m(-3), which is representative for all countries and environmental conditions, the tracheobronchial fraction represents approximately 10% and the alveolar fraction approximately 8% of the total particles suspended in air. However, from the environmental risk point of view, an exposure to PGEs in traffic-related ambient air is at least three orders of magnitude below the levels for which adverse health effects might theoretically occur (of approx. 100 ng m(-3)). Therefore, today inhalation exposure to PGEs from automotive catalysts does not seem to pose a direct health risk to the general population. Even though the data available today indicate no obvious health effects, there are still a number of aspects related to PGEs and catalysts that justify further research. First, continual monitoring of changes in PGE levels in air and road dust is warranted, to make sure that there is no dramatic increase from today's levels. Secondly, more detailed information on the chemical composition of the PGE-containing substances or complexes leaving the catalyst surface and the size distribution of the PGE-containing particles released during driving will facilitate a more in-depth human risk assessment.
A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80,000 km. Two were gasoline engine catalysts (Pt-Pd-Rh and Pd-Rh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (one-two orders of magnitude) for the content of noble metals emitted. The samples collected from 30,000-80,000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment.
Explore the source record for details and available documents.
Store-operated Ca(2+) channels (SOC) are expressed in cultured human mesangial cells and activated by epidermal growth factor through a pathway involving protein kinase C (PKC). We used fura-2 fluorescence and patch clamp experiments to determine the role of PKC in mediating the activation of SOC after depletion of internal stores by thapsigargin. The measurements of intracellular Ca(2+) concentration ([Ca(2+)](i)) revealed that the thapsigargin-induced Ca(2+) entry pathway was abolished by calphostin C, a protein kinase C inhibitor. The PKC activator, phorbol 12-myristate 13-acetate (PMA), promoted a Ca(2+) influx that was significantly attenuated by calphostin C and La(3+) but not by diltiazem. Neither PMA nor calphostin C altered the thapsigargin-induced initial transient rise in [Ca(2+)](i). In cell-attached patch clamp experiments, the thapsigargin-induced activation of SOC was potentiated by PMA and abolished by both calphostin C and staurosporine. However, SOC was unaffected by thapsigargin when clamping [Ca(2+)](i) with 1,2-bis (o-Aminophenoxy)ethane-N,N,N',N'tetraacetic acid tetra(acetoxymethyl)ester. In the absence of thapsigargin, PMA and phorbol 12, 13-didecanoate evoked a significant increase in NP(O) of SOC, whereas calphostin C did not affect base-line channel activity. In inside-out patches, SOC activity ran down immediately upon excision but was reactivated significantly after adding the catalytic subunit of 0.1 unit/ml of PKC plus 100 microm ATP. Neither ATP alone nor ATP with heat-inactivated PKC rescued a rundown of SOC. Metavanadate, a general protein phosphatase inhibitor, also enhanced SOC activity in inside-out patches. Bath [Ca(2+)] did not significantly affect the channel activity in inside-out patch. These results indicate that the depletion of Ca(2+) stores activates SOC by PKC-mediated phosphorylation of the channel proteins or a membrane-associated complex.
A new strategy for characterisation of airborne uranium contamination based on elemental/isotopic analysis of tree bark is described. Bark samples collected at Tokai-mura (Japan) were subjected to high sensitivity ICP mass spectrometric analysis; for control purposes, samples from the remote Yakushima island (Southern Japan) and central Tokyo were also analysed. The uranium contents of tree bark for Tokyo and Yakushima were of similar magnitude to that at Tokai-mura (U, 0.01-1.0 microg/g - all samples), however, there were marked differences in isotope ratio values between the sites. Whereas natural uranium isotope ratio values (235U/238U, 0.0072) were observed for Yakushima and Tokyo, non-natural and natural signatures (235U/238U, 0.00697-0.01448) were realised at Tokai-mura. These findings are consistent with the release of enriched uranium at Tokai-mura.
BACKGROUND: Seventy-nine consecutive patients with primary choroidal melanoma were treated with 198 Au plaque brachytherapy at the British Columbia Cancer Agency (BCCA) between 1992 and 1998 with perioperative ultrasound to confirm plaque placement. Seventy-seven of the 79 patients were analyzable for this study. RESULTS: Five year actuarial disease specific survival, enucleation free survival, and local control are 95, 94, and 98%, respectively. There were four melanoma related deaths, all secondary to liver metastases. CONCLUSIONS: The BCCA experience in selected patients with choroidal melanomas treated with 198Au plaque brachytherapy has resulted in excellent survival and local control with minimal significant toxicity while preserving the globe. Our results using 198 Au seeds are comparable to other series using 125I, 60Co, and 106Ru at other centers.
A new strategy for characterisation of airborne uranium contamination based on ICP mass spectrometric analysis of tree bark is described. The uranium content of tree barks (50 samples) obtained from diverse locations (remote, rural, industrial) varied over almost four orders of magnitude (0.001-8.3 micrograms/g U) with maximum concentrations recorded in the vicinity of a nuclear fuel fabrication plant (0.70-8.3 micrograms/g U). Elevated concentrations were also observed near a coal-fired power station (0.25-0.38 microgram/g U). Isotopic analysis revealed significant deviation from the natural uranium isotope ratio (235U/238U, 0.00725) at four nuclear installations (235U/238U, 0.0055-0.0097). These findings indicate that tree bark serves as an effective biomonitor for uranium and, with isotopic analysis, discrimination between nuclear and non-nuclear emissions is realised.
Samples of tree bark were collected from four locations in Northern England (a typical rural site, a coal-fired power station, a uranium (isotopic) enrichment plant and a nuclear fuel fabrication facility), to assess the nature and extent of airborne uranium and thorium contamination. The U and Th concentrations of bark were determined by inductively coupled plasma mass spectrometry after conventional nebulisation of bark digests, whilst measurement of 235U/238U isotopic ratio utilised high efficiency nebulisation. Uranium concentrations varied between and within the sites (range, 0.01-12 micrograms g-1), with maximum values recorded within 1 km of the nuclear fuel fabrication plant (Springfields). In comparison, the concentration of Th in bark was low (mean, 0.018 microgram g-1) at all sites with the exception of the area affected by coal combustion (0.2-0.8 microgram g-1). The U/Th ratio varied from 0.5 to 3900 compared with the average crustal ratio of 0.3. Low values (< 2) were recorded at the 'coal' and 'rural' sites whilst Capenhurst and Springfields showed high values indicating the relative magnitude of uranium elevation. Significant enrichment of the natural 235U/238U ratio (0.00725) was observed near the nuclear installations, in particular, the enrichment plant (Capenhurst).
Our previous study (27) showed that the cardiac sympathetic afferent reflex (CSAR) was enhanced in dogs with congestive heart failure. The aim of this study was to test whether blood volume expansion, which is one characteristic of congestive heart failure, potentiates the CSAR in normal dogs. Ten dogs were studied with sino-aortic denervation and bilateral cervical vagotomy. Arterial pressure, left ventricular pressure, left ventricular epicardial diameter, heart rate, and renal sympathetic nerve activity were measured. Coronary blood flow was also measured and, depending on the experimental procedure, controlled. Blood volume expansion was carried out by infusion of isosmotic dextran into a femoral vein at 40 ml/kg at a rate of 50 ml/min. CSAR was elicited by application of bradykinin (5 and 50 microg) and capsaicin (10 and 100 microg) to the epicardial surface of the left ventricle. Volume expansion increased arterial pressure, left ventricular pressure, left ventricular diameter, and coronary blood flow. Volume expansion without controlled coronary blood flow only enhanced the RSNA response to the high dose (50 microg) of epicardial bradykinin (17. 3 +/- 1.9 vs. 10.6 +/- 4.8%, P < 0.05). However, volume expansion significantly enhanced the RSNA responses to all doses of bradykinin and capsaicin when coronary blood flow was held at the prevolume expansion level. The RSNA responses to bradykinin (16. 9 +/- 4.1 vs. 5.0 +/- 1.3% for 5 microg, P < 0.05, and 28.9 +/- 3.7 vs. 10.6 +/- 4.8% for 50 microg, P < 0.05) and capsaicin (29.8 +/- 6.0 vs. 9.3 +/- 3.1% for 10 microg, P < 0.05, and 34.2 +/- 2.7 vs. 15.1 +/- 2.7% for 100 microg, P < 0.05) were significantly augmented. These results indicate that acute volume expansion potentiated the CSAR. These data suggest that enhancement of the CSAR in congestive heart failure may be mediated by the concomitant cardiac dilation, which accompanies this disease state.
We present a new statistical model for linking spatial variation in ambient air pollution to mortality. The model incorporates risk factors measured at the individual level, such as smoking, and at the spatial level, such as air pollution. We demonstrate that the spatial autocorrelation in community mortality rates, an indication of not fully characterizing potentially confounding risk factors to the air pollution-mortality association, can be accounted for through the inclusion of location in the model assessing the effects of air pollution on mortality. Our methods are illustrated with an analysis of the American Cancer Society cohort to determine whether all cause mortality is associated with concentrations of sulfate particles. The relative risk associated with a 4.2 microg/m(3) interquartile range of sulfate distribution for all causes of death was 1.051 (95% confidence interval 1.036-1.066) based on the Cox proportional hazards survival model, assuming subjects were statistically independent. Inclusion of community-based random effects yielded a relative risk of 1.055 (1.033, 1.077), which represented a doubling in the residual variance compared to that estimated by the Cox model. Residuals from the random-effects model displayed strong evidence of spatial autocorrelation (p = 0.0052). Further inclusion of a location surface reduced the sulfate relative risk and the evidence for autocorrelation as the complexity of the location surface increased, with a range in relative risks of 1.055-1.035. We conclude that these data display both extravariation and spatial autocorrelation, characteristics not captured by the Cox survival model. Failure to account for extravariation and spatial autocorrelation can lead to an understatement of the uncertainty of the air pollution association with mortality.
The first control of a malignant tumor in vivo by porphyrin- mediated boron neutron capture therapy (BNCT) is described. In mice bearing implanted EMT-6 mammary carcinomas, boron uptake using a single injection of either p-boronophenylalanine (BPA) or mercaptoundecahydrododecaborane (BSH) was compared with either a single injection or multiple injections of the carboranylporphyrin CuTCPH. The BSH and BPA doses used were comparable to the highest doses of these compounds previously administered in a single injection to rodents. For BNCT, boron concentrations averaged 85 microg (10)B/g in the tumor and 4 microg (10)B/g in blood 2 days after the last of six injections (over 32 h) that delivered a total of 190 microg CuTCPH/g body weight. During a single 15, 20, 25 or 30 MW-min exposure to the thermalized neutron beam of the Brookhaven Medical Research Reactor, a tumor received average absorbed doses of approximately 39, 52, 66 or 79 Gy, respectively. A long-term (>200 days) tumor control rate of 71% was achieved at a dose of 66 Gy with minimal damage to the leg. Equivalent long-term tumor control by a single exposure to 42 Gy X rays was achieved, but with greater damage to the irradiated leg.