Independent dose per monitor unit review of eight U.S.A. proton treatment facilities.

PURPOSE: Compare the dose per monitor unit at different proton treatment facilities using three different dosimetry methods. METHODS: Measurements of dose per monitor unit were performed by a single group at eight facilities using 11 test beams and up to six different clinical portal treatment sites. These measurements were compared to the facility reported dose per monitor unit values. RESULTS: Agreement between the measured and reported doses was similar using any of the three dosimetry methods. Use of the ICRU 59 ND,w based method gave results approximately 3% higher than both the ICRU 59 NX and ICRU 78 (TRS-398) ND,w based methods. CONCLUSIONS: Any single dosimetry method could be used for multi-institution trials with similar conformity between facilities. A multi-institutional trial could support facilities using both the ICRU 59 NX based and ICRU 78 (TRS-398) ND,w based methods but use of the ICRU 59 ND,w based method should not be allowed simultaneously with the other two until the difference is resolved.

The Chelsea critical care physical assessment tool (CPAx): validation of an innovative new tool to measure physical morbidity in the general adult critical care population; an observational proof-of-concept pilot study.

OBJECTIVE: To develop a scoring system to measure physical morbidity in critical care - the Chelsea Critical Care Physical Assessment Tool (CPAx). METHOD: The development process was iterative involving content validity indices (CVI), a focus group and an observational study of 33 patients to test construct validity against the Medical Research Council score for muscle strength, peak cough flow, Australian Therapy Outcome Measures score, Glasgow Coma Scale score, Bloomsbury sedation score, Sequential Organ Failure Assessment score, Short Form 36 (SF-36) score, days of mechanical ventilation and inter-rater reliability. PARTICIPANTS: Trauma and general critical care patients from two London teaching hospitals. RESULTS: Users of the CPAx felt that it possessed content validity, giving a final CVI of 1.00 (P<0.05). Construct validation data showed moderate to strong significant correlations between the CPAx score and all secondary measures, apart from the mental component of the SF-36 which demonstrated weak correlation with the CPAx score (r=0.024, P=0.720). Reliability testing showed internal consistency of α=0.798 and inter-rater reliability of κ=0.988 (95% confidence interval 0.791 to 1.000) between five raters. CONCLUSION: This pilot work supports proof of concept of the CPAx as a measure of physical morbidity in the critical care population, and is a cogent argument for further investigation of the scoring system.

Quantitative human health risk assessment for 1,3-butadiene based upon ovarian effects in rodents.

A case study was prepared for noncancer risk assessment of 1,3-butadiene (BD) based upon the ovarian atrophy effects in rodents with specific consideration of the guidelines described by NAS (2009). Ovarian toxicity has been identified in the past as a sensitive endpoint for BD, and serves as the basis for noncancer risk assessment by regulatory agencies. A meta-analysis was conducted in which the available dose-response data from rats and mice were normalized using an internal dose estimate (DEB in blood) that is causally related to ovarian toxicity. A time-to-response (multistage-Weibull) model was used to simultaneously fit the pooled rodent data sets with exposure durations ranging from 13 to 105weeks. Human variation in ovarian follicle count was assumed to reflect variation in sensitivity to the adverse effects associated with follicle depletion (i.e., premature menopause). Information on follicle count in women was used in two ways: (1) the window of susceptibility (from birth to menopause) was defined as 49.6years for women born with an average follicle count, 38.7years for women born with a low follicle count, and 60.0years for women born with a high follicle count; and (2) follicle count was assumed to reflect human susceptibility due to toxicodynamic factors. The multistage-Weibull model was used to predict dose-response curves for three scenarios (average, low, and high follicle counts at birth to generate reference concentration values ranging from 0.2 to 20ppm). This case study illustrates how information on mode of action can be used to guide key decisions in the dose-response assessment with respect to identifying a dose measure, low-dose extrapolation method, background exposure, and sensitive subpopulations.

Three-Dimensional Dosimetry of a Beta-Emitting Radionuclide Using PRESAGE Dosimeters.

Three-dimensional dose distributions from liquid brachytherapy were measured using PRESAGE(®) dosimeters. The dosimeters were exposed to Y-90 for 5.75 days and read by optical tomography. The distributions are consistent with estimates from beta dose kernels.

Ultrasound detection of a subperiosteal abscess secondary to coalescent otomastoiditis.

We report the unusual ultrasound appearance of coalescent otomastoiditis with subperiosteal abscess in a 3-month-old boy with a 1-week history of an enlarging lump behind the left ear. Ultrasound examination of the lump revealed subcutaneous oedema with an abscess extending from a defect in the cranial vault as a result of extension of the inflammatory process. We believe that this sonographic appearance has not been previously described in the published literature.

National clinical sentinel audit of evidence-based prescribing for older people.

OBJECTIVES: To audit the performance of hospitals in evidence-based prescribing. SETTING: All hospitals in England were invited to participate. The audit was completed in 62 hospitals. SUBJECTS: Prescribing and clinical data were collected on 100 consecutive medical inpatients aged >/= 65 years at each site, enabling evaluation of eight prescribing indicators before and after intervention. The data were collected using a specifically designed database. INTERVENTIONS: The results of the first audit were available immediately from the software and a national report with locally identifiable information was returned to hospitals. Hospitals were encouraged to design and deliver their own intervention strategy. A questionnaire was sent to all hospitals to document prioritization of indicators. RESULTS: Generic names were used for 36 061 (82.6%) in 1999 and 39 188 (86.4)% in 2000. In 1999, 50% (3074) of patients had documentation of allergy status. This increased to 60% (3684) in 2000. For 21.2% of patients prescribed paracetamol in 1999 and 18.1% in 2000, the prescription was written such that it was possible to exceed the maximum recommended dose of 4 g in 24 hours. Long-acting hypoglycaemic drugs were prescribed to 29 patients in 1999 and 20 patients in 2000. Anti-thrombotics were used appropriately for 54% (520/966) of patients in atrial fibrillation in the first audit and 57% (579/1019) in the second audit. The appropriate use of aspirin increased from 91% (595/651) to 94% (725/772) and the appropriate use of benzodiazepines dropped from 49% (537/1088) to 47% (460/966) between the audits. For three indicators, the allocating of a high priority translated into a bigger improvement between the audits. CONCLUSIONS: Local ownership of data and the quality improvement process, and provision of national benchmarking data did not result in a significant improvement in prescribing in the second audit.

National sentinel clinical audit of evidence-based prescribing for older people: methodology and development.

RATIONALE, AIMS AND OBJECTIVES: This national clinical audit aimed to develop and implement a methodology to assess the appropriateness of prescribing for patients over the age of 65 in hospitals, general practice and nursing homes. METHODS: Organizations providing health care in the National Health Service in these three sectors were recruited into multi-disciplinary and inter-organizational local coalition teams. Prescription data and relevant clinical data were collected electronically on a customized database. The appropriateness of prescribing for specific conditions among the patients sampled was assessed by simple computerized algorithms, and users were provided with feedback to stimulate discussion and change. Use of the software tool was demonstrated to be feasible and its data reliable. Participants were re-audited, after a period of nationally guided and locally driven intervention, to evaluate levels of change. Local efforts to stimulate change and barriers to change were collected qualitatively. RESULTS AND CONCLUSIONS: The investigation revealed encouraging results and demonstrated the ability of audit to improve the quality of clinical services in given circumstances, although a multiplicity of questions relating to cost and methodology remain to be addressed.

Ratiometric measurement of intracellular pH of cultured cells with BCECF in a fluorescence multi-well plate reader.

A number of methods have been developed to measure intracellular pH (pHi) because of its importance in intracellular events. A major advance in accurate pHi measurement was the development of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). We have used a fluorescence multi-well plate reader and a ratiometric method for determining pHi in primary cultures of rabbit corneal epithelial (CE) cells with BCECF. Fluorescence was measured at excitation wavelengths of 485 +/- 11 nm and 395 +/- 12.5 nm, with emission detected at 530 +/- 15 nm. Cells grown in multi-well plates were loaded with 4 microM BCECF for 30 min at 37 degrees C. Resting pHi was 7.34 +/- 0.03 (2 cultures, N = 5 wells). Changes in pHi determined with the fluorescence multi-well plate reader after the addition and removal of NH4Cl or sodium lactate were comparable to changes in cells analyzed with a digitized fluorescence imaging system. A concentration-response relationship involving changes in pHi was easily demonstrated in CE cells after treatment with ionomycin, a calcium ionopore. Low doses of ionomycin (2.5-5 microM), produced a prolonged acidification; 7.5 microM ionomycin produced a transient acidification; and 10 microM ionomycin resulted in a slight alkalinization. We conclude that accurate pHi measurements can be obtained with a ratiometric method with BCECF in a multi-well plate reader. This technology may simplify screening studies evaluating effects of hormones, growth factors, or toxicants on pHi homeostasis.

Loss of cytoskeletal support is not sufficient for anoxic plasma membrane disruption in renal cells.

The goal of this study was to determine whether anoxic membrane disruption is initiated by loss of cytoskeletal support in rabbit renal proximal tubules (PT). We specifically tested 1) whether cytoskeletal perturbation affects membrane integrity under normoxia, 2) whether cytoskeletal perturbation potentiates anoxic membrane damage, and 3) whether the membrane protection by glycine depends on cytoskeletal integrity. Cytoskeletal perturbation was achieved with 10 microM cytochalasin D (CD) because it selectively disturbs F-actin organization and has similar effects as anoxia on the cytoskeleton of PT. During normoxia, CD caused decreased basal F-actin content, microvillar breakdown, and membrane-cytoskeleton dissociation, as revealed by the use of laser tweezers. However, membrane integrity was not altered by CD, as monitored by lactate dehydrogenase release. CD pretreatment of PT did not potentiate anoxic membrane damage. Finally, plasma membrane protection by glycine during anoxia remained in CD-pretreated PT despite loss of cytoskeletal support. These results demonstrate that loss of cytoskeletal support is not sufficient for anoxic plasma membrane disruption.

Prolonged adverse effects of benzalkonium chloride and sodium dodecyl sulfate in a primary culture system of rabbit corneal epithelial cells.

This investigation was undertaken to determine prolonged adverse effects of benzalkonium chloride (BzCl), a cationic surfactant, and sodium dodecyl sulfate (SDS), an anionic surfactant, after an initial treatment of and subsequent removal from a primary culture system of rabbit corneal epithelial cells. Metabolic integrity and cell growth were evaluated at specified periods after a 1-hr treatment with the surfactants because of their importance in tissue repair. Intracellular calcium ([Ca2+]i) and intracellular pH (pHi) were also measured because of their importance in cellular homeostasis. ATP/ADP ratios were used to assess metabolic integrity, and propidium iodide staining of cells was used to measure relative cell number and cell growth. Digitized fluorescence imaging was used to measure [Ca2+]i with fura-PE3 and pHi with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). BzCl induced a concentration-dependent decrease in ATP/ADP ratios 24 hr after its removal from the cultures, whereas SDS had minimal effects on metabolic integrity throughout the 48-hr postexposure measurement period. The proliferative response of cultures treated with SDS, however, was decreased when compared with BzCl-treated cells. BzCl induced an increase in [Ca2+]i, whereas SDS decreased [Ca2+]i 1-3 hr after removal of surfactants. BzCl produced a sustained decrease in pHi in surviving cells 1-4 hr after its removal, with a return to control values at 24-48 hr. SDS transiently increased pHi 1 hr after its removal and decreased pHi at the 48-hr post-treatment period. In conclusion, the two surfactants in vitro had distinctly different prolonged effects on corneal epithelial cells, which may suggest that BzCl and SDS differentially affect cellular recovery in vivo.

Interactions of intracellular pH and intracellular calcium in primary cultures of rabbit corneal epithelial cells.

Homeostasis of intracellular calcium ([Ca++]i) and pH (pHi) is important in the cell's ability to respond to growth factors, to initiate differentiation and proliferation, and to maintain normal metabolic pathways. Because of the importance of these ions to cellular functions, we investigated the effects of changes of [Ca++]i and pHi on each other in primary cultures of rabbit corneal epithelial cells. Digitized fluorescence imaging was used to measure [Ca++]i with fura-2 and pHi with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Resting pHi in these cells was 7.37 +/- 0.05 (n = 20 cells) and resting [Ca++]i was 129 +/- 10 nM (n = 35 cells) using a nominally bicarbonate-free Krebs Ringer HEPES buffer (KRHB), pH 7.4. On exposure to 20 mM NH4Cl, which rapidly alkalinized cells by 0.45 pH units, an increase in [Ca++]i to 215 +/- 14 nM occurred. Pretreatment of the cells with 100 microM verapamil or exposure to 1 mM ethylene bis-(oxyethylenenitrilo)-tetraacetic acid (EGTA) without extracellular calcium before addition of 20 mM NH4Cl did not abolish the calcium increase, suggesting that the source of the calcium transient was from intracellular calcium stores. On removal of NH4Cl or addition of 20 mM sodium lactate, there were minimal changes in calcium even though pHi decreased. Treatment of CE cells with the calcium ionophores, ionomycin and 4-bromo A23187, increased [Ca++]i, but produced a biphasic change in pHi. Initially, there was an acidification of the cytosol, and then an alkalinization of 0.10 to 0.11 pH units above initial values. When [Ca++]i was decreased by treating the cells with 5 mM EGTA and 20 microM ionomycin, pHi decreased by 0.35 +/- 0.02 units. We conclude that an increase in pHi leads to an increase in [Ca++]i in rabbit corneal epithelial cells; however, a decrease in pHi leads to minor changes in [Ca++]i. The ability of CE cells to maintain proper calcium homeostasis when pHi is decreased may represent an adaptive mechanism to maintain physiological calcium levels during periods of acidification, which occur during prolonged eye closure.

Disinfection and sterilization of composite polishing instruments.

PURPOSE: To evaluate the efficacy of several methods of sterilization and disinfection on two different types of composite finishing and polishing instruments. MATERIALS AND METHODS: The instruments consisted of a proprietary light-cured resin cup impregnated with an abrasive and a silicon dioxide-impregnated rubber cup. Chemical and physical methods included treatment with iodophor, synthetic phenol, glutaraldehyde, microwaving, autoclaving, and chemiclaving. RESULTS: Glutaraldehyde (Vital Defense-S) was an effective disinfectant; however, other chemical (cold) disinfectants overall, were not reliable. Autoclaving, chemiclaving, and microwaving all provided to be effective means of sterilization.

A digitized fluorescence imaging study on the effects of local anesthetics on cytosolic calcium and mitochondrial membrane potential in cultured rabbit corneal epithelial cells.

It has been documented by several investigators that local anesthetics displace calcium from calcium binding sites and alter the functioning of different calcium regulating systems. Local anesthetics have also been shown to have adverse effects on mitochondrial function and interact with cytoskeletal elements. Few studies have addressed the role that a potential disturbance of calcium homeostasis and mitochondrial function may have on the toxicity caused by local anesthetics in corneal epithelial cells. This investigation was undertaken to evaluate the effects of tetracaine (TTC), proparacaine (PPC), and cocaine (CC) on cytosolic calcium and mitochondrial membrane potential in primary cultures of rabbit corneal epithelial cells. Previous studies by our laboratory documented that the local anesthetics produce toxicity after 30 to 60 min of treatment. In this study, the cells were treated for 15 min, a time when minimal cell damage occurred. The following concentrations of local anesthetics were used to treat the cells: TTC, 0.5-2.5 mM; PPC, 1-5 mM; and CC, 4-10 mM. We utilized the technology of digitized fluorescence imaging to measure changes in intracellular calcium ([Ca2+]i) with fura-2 and mitochondrial membrane potential (delta psi) with rhodamine 123. A dose-dependent increase in [Ca2+]i was evident after treatment with each local anesthetic. Concentrations equal or greater than 2.5 mM TTC dissipated delta psi. A rise in [Ca2+]i preceded any loss of delta psi caused by TTC. PPC at high concentrations (4-5 mM) occasionally dissipated delta psi but this was not a consistent finding. The effects of CC on delta psi could not be evaluated accurately because of the extensive morphological alterations that occurred after treatment. We conclude that TTC, PPC, and CC elevate [Ca2+]i before cytotoxicity occurs and disruptions in calcium homeostasis may contribute to their toxicity.

Comparative toxicity of tetracaine, proparacaine and cocaine evaluated with primary cultures of rabbit corneal epithelial cells.

Cocaine was first used as a topical anesthetic for the eye by Dr Carl Koller in 1884. It became evident that this agent produced erosion of the corneal epithelium in high doses or with repeated use. Synthetic local anesthetics such as tetracaine and proparacaine were developed which were more potent and less toxic than cocaine, but still produced corneal epithelium defects if used chronically. This investigation was undertaken to compare and rank the cytotoxicity of the most commonly used ocular local anesthetics, tetracaine, proparacaine and cocaine, with primary cultures of rabbit corneal epithelial cells. Cultures were exposed to either low concentrations of local anesthetics for 4-24 hr or to higher concentrations of local anesthetics for 15-120 min. Plasma membrane integrity was evaluated by measuring leakage of the cytosolic enzyme, lactate dehydrogenase, into the medium. Cell shape changes were evaluated by observing morphological changes. Mitochondrial dehydrogenase activity and cell viability were assessed by measuring 3-(4,5-dimethythiazol-2yl)-2,5-diphenyl tetrazolium bromide reduction. The cytotoxicity of the local anesthetics as evaluated by the lactate dehydrogenase leakage cytotoxicity test was ranked as follows: tetracaine (EC50 = 0.96 mM) >> proparacaine (EC50 = 4.4 mM) > cocaine (EC50 = 9.7 mM). The mitochondrial reduction assay seemed to be more sensitive than the lactate dehydrogenase leakage test in predicting toxicity: tetracaine (EC50 = 0.81 mM) >> proparacaine (EC50 = 3.4 mM) > cocaine (EC50 = 7.1 mM). When corneal epithelial cells were treated with local anesthetics, marked morphological changes occurred at concentrations that did not cause a decrease in viability. This was especially true for cocaine-treated cells. Tetracaine and proparacaine have the same anesthetic potency in vivo, although tetracaine is considered to be more irritating than proparacaine. This in vitro study showed that tetracaine was approximately four times more toxic than proparacaine. Cocaine was less toxic in vitro than proparacaine and tetracaine when compared on an equimolar basis, but in vivo it may be more toxic because of the higher concentrations that must be used to obtain the same degree of anesthesia as well as its marked effects on cell morphology.

A digitized fluorescence imaging study of intracellular free calcium, mitochondrial integrity and cytotoxicity in rat renal cells exposed to ionomycin, a calcium ionophore.

The objective of this study was to explore the role of extracellular Ca2+ and mitochondrial integrity in ionomycin-induced cytotoxicity in primary cultures of rat kidney cortical epithelial cells using digitized fluorescence imaging (DFI), which is a powerful tool for continuously observing the dynamic intracellular biochemistry of single living cells. Using DFI, intracellular free calcium ion concentration ([Ca2+]i), mitochondrial membrane potential and loss of cell viability in individual rat renal cortical epithelial cells were examined temporally by fura-2, rhodamine 123 (Rh-123) and propidium iodide (PI), respectively. Images were taken within 10 min after exposure to 5 and 10 microM ionomycin. These three parameters, [Ca2+]i, mitochondrial membrane potential and cell viability, were also measured in populations of cells by a multiwell fluorescence scanner with fluo-3, Rh-123 and PI, respectively. Cytotoxicity was also assessed by two colorimetric cytotoxicity tests (LDH leakage and mitochondrial MTT reduction). Using DFI, the fluorescence scanner and the colorimetric cytotoxicity tests, we found that exposure of primary cultures of rat kidney cortical epithelial cells to high concentrations of ionomycin (5 and 10 microM) caused a rapid and sustained rise in [Ca2+]i, which preceded dissipation of the mitochondrial membrane potential and loss of cell viability and that chelation of extracellular Ca2+ with EGTA attenuated these responses. We demonstrated the value of using DFI to continuously observe the dynamic intracellular biochemistry of single living cells by establishing a sequence of elevated [Ca2+]i, dissipation of mitochondrial membrane potential and cytotoxicity. We conclude that a combination of the influx of extracellular Ca2+ and loss of mitochondrial integrity may be responsible for the cytotoxicity observed in individual renal cells and populations of renal cells after treatment with ionomycin.

Cancer trends unique to Georgia.

Using information from 1980 through 1991 Cancer Statistics, published by the American Cancer Society, we assigned a rank order of new cancer cases for Georgia and eight other states. Female breast, colon and rectum, lung, oral, uterus, prostate, pancreas, and leukemia are the site-specific cancers that were considered. There was an increasing trend in Georgia for colon and rectal cancer and breast cancer during this study period. This increased trend for colorectal and breast cancer in Georgia was not apparent in the other index states. Possible influences of population, physician practices, and socioeconomic factors are considered. The results of this project indicate that further study is needed to evaluate this trend, possibly by examination of regional differences within the state of Georgia, especially with regard to environmental factors.

Evaluation of surfactant cytotoxicity potential by primary cultures of ocular tissues: I. Characterization of rabbit corneal epithelial cells and initial injury and delayed toxicity studies.

This investigation was undertaken to develop cytotoxicity assay systems using primary cultures of rabbit corneal epithelial cells as an experimental model to evaluate oculotoxic agents and the ability of these in vitro assay systems to predict irritancy potential and delayed toxicity. We have characterized the epithelial nature of the cultures by identifying keratins with antikeratin antibodies (AE1/AE3) and by demonstrating metabolic enzymes important to the integrity of the cells: lactate dehydrogenase, glucose 6-phosphate dehydrogenase and aldolase. Eight surfactants were compared and ranked according to their cytotoxic potential. We evaluated cytotoxicity by measuring leakage of the cytosolic enzyme, lactate dehydrogenase, into the medium, by making morphological observations and by assessing lysosomal neutral red uptake and mitochondrial 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction. The cells were treated for 1 h with the surfactants and the possibility of delayed toxicity was evaluated 24 h after removal of the surfactant. The cytotoxicity of the different types of surfactants as shown by all the tests was cationic > anionic = amphoteric > non-ionic. Triton X-100, a non-ionic surfactant but a severe irritant, had a ranking similar to anionic surfactants. The in vitro rankings corresponded well to reported in vivo Draize rabbit eye test data. The 24-h test for lactate dehydrogenase leakage showed that mild and non-irritating surfactants did not demonstrate any subsequent damage after a 1-h exposure, but the extreme and severe surfactants continued to show further damage after the 1-h exposure. These in vitro findings were similar to reported in vivo results. The neutral red and MTT tests did not adequately predict the prolonged toxicity of the more irritating surfactants, as was demonstrated by the lactate dehydrogenase leakage test. We conclude that in vitro cytotoxicity assays using primary cultures of rabbit corneal epithelial cells may be used to rank the cytotoxic potential of surfactants, but only the lactate dehydrogenase leakage test was able to assess prolonged cell injury.

Underrecognition of patients' psychosocial distress in a university hospital medical clinic.

Seventeen areas of psychosocial distress were evaluated in 87 university hospital internal medicine clinic patients by a self-administered questionnaire and a psychiatric interview. These patients' internists then predicted the patients' distress level in each area. Their predictions correlated significantly with their patients' self-reports of distress-level problems in only 3 of the 17 areas. Even when the internists felt that they had sufficient information to make an accurate prediction, their perceptions were often erroneous, including evaluations of such areas as suicidal ideation and drug use. These data suggest the need for active psychiatric education components in internal medicine training programs.

Family physicians' perceptions of psychosocial disorders: survey report and educational implications.

One-hundred seventy-seven family physicians were surveyed regarding their perceptions of the types of psychosocial problems encountered in their practices, the amount of time they felt they devoted to each problem, and their interests regarding continuing psychiatric education. Patients with "multiple somatic complaints" and "symptoms of emotional distress" were reported as being encountered most frequently. Marital and family problems, alcoholism and sexual dysfunction were also ranked highly. The physicians indicated the highest interest in managing these disorders in addition to treatment of the suicidal patient. The implications of these results for psychiatric educators and liaison psychiatrists are discussed. The authors recommend using DSM-III diagnostic criteria applicable to these syndromes in formulating educational programs for primary care physicians.