Effects of a computerized working memory training program on working memory, attention, and academics in adolescents with severe LD and comorbid ADHD: a randomized controlled trial

BACKGROUND

Youths with coexisting learning disabilities (LD) and attention deficit hyperactivity disorder (ADHD) are at risk for poor academic and social outcomes. The underlying cognitive deficits, such as poor working memory (WM), are not well targeted by current treatments for either LD or ADHD. Emerging evidence suggests that WM might be improved by intensive and adaptive computerized training, but it remains unclear whether this intervention would be effective for adolescents with severe LD and comorbid ADHD.

METHODS

A total of sixty 12- to 17-year olds with LD/ADHD (52 male, 8 female, IQ > 80) were randomized to one of two computerized intervention programs: working memory training (Cogmed RM) or math training (Academy of Math) and evaluated before and 3 weeks after completion. The criterion measures of WM included auditory-verbal and visual-spatial tasks. Near and far transfer measures included indices of cognitive and behavioral attention and academic achievement.

RESULTS

Adolescents in the WM training group showed greater improvements in a subset of WM criterion measures compared with those in the math-training group, but no training effects were observed on the near or far measures. Those who showed the most improvement on the WM training tasks at school were rated as less inattentive/hyperactive at home by parents.

CONCLUSIONS

Results suggest that WM training may enhance some aspects of WM in youths with LD/ADHD, but further development of the training program is required to promote transfer effects to other domains of function.

Comparison of powered and conventional air-purifying respirators during simulated resuscitation of casualties contaminated with hazardous substances

BACKGROUND

Advanced life support of patients contaminated with chemical, biological, radiological or nuclear (CBRN) substances requires adequate respiratory protection for medical first responders. Conventional and powered air-purifying respirators may exert a different impact during resuscitation and therefore require evaluation. This will help to improve major incident planning and measures for protecting medical staff.

METHODS

A randomised crossover study was undertaken to investigate the influence of conventional negative pressure and powered air-purifying respirators on the simulated resuscitation of casualties contaminated with hazardous substances. Fourteen UK paramedics carried out a standardised resuscitation algorithm inside an ambulance vehicle, either unprotected or wearing a conventional or a powered respirator. Treatment times, wearer mobility, ease of communication and ease of breathing were determined and compared.

RESULTS

In the questionnaire, volunteers stated that communication and mobility were similar in both respirator groups while breathing resistance was significantly lower in the powered respirator group. There was no difference in mean (SD) treatment times between the groups wearing respiratory protection and the controls (245 (19) s for controls, 247 (17) s for conventional respirators and 250 (12) s for powered respirators).

CONCLUSIONS

Powered air-purifying respirators improve the ease of breathing and do not appear to reduce mobility or delay treatment during a simulated resuscitation scenario inside an ambulance vehicle with a single CBRN casualty.

The Efficacies of 3,4,3-LIHOPO and DTPA for Enhancing the Excretion of Plutonium and Americium from the Rat: Comparison with Other Siderophore Analogues

With DTPA as a comparison, the siderophore analogue code named 3,4,3-LIHOPO has been tested for its ability to remove 238Pu and 241Am from rats after their inhalation or intravenous injection as nitrate. The most effective treatment regimen for inhaled Pu was the repeated administration of 30 mumol kg-1 3,4,3-LIHOPO. By 7 days after exposure, the Pu contents of the lungs and total body were reduced respectively to 2 and 4% of those in untreated animals. These values were six and three times less than when DTPA was administered using the same protocol. For inhaled Am, 3,4,3-LIHOPO and DTPA were considered equally effective, the lung and total body contents being reduced respectively to 13 and 10% of those in controls. Some animals showed slight degenerative changes in the liver and proximal tubules of the kidneys after the repeated administration of 30 mumol kg-1 of 3,4,3-LIHOPO; however these changes were less marked than after DTPA treatment. After the intravenous injection of Pu, the most effective regimen was the single administration of 3 mumol kg-1 3,4,3-LIHOPO. The body content at 7 days was reduced to 7% controls compared with 19% after the repeated administration of 30 mumol kg-1 DTPA. At a dosage of 30 mumol kg-1, 3,4,3-LIHOPO was less effective owing to the higher retention of Pu in the liver. With repeated dosages of 30 mumol kg-1 3,4,3-LIHOPO was more effective than DTPA for the decorporation of Am; the body contents were 16 and 31% of those in controls respectively. Importantly, the body content was still reduced to 28% of control after a single administration of 3 mumol kg-1. The ligand 3,4,3-LIHOPO, which is also superior to other siderophore analogues, could represent a most significant development in the decorporation of Pu and Am.

E-learning and the future of dental education: opinions of administrators and information technology specialists

The digital revolution and growth of the Internet have led to many innovations in the area of electronic learning (e-learning). To survive and prosper, educators must be prepared to respond creatively to these changes. Administrators and information technology specialists at six dental schools and their parent institutions were interviewed regarding their opinions of the impact that e-learning will have on the future of dental education. Interview questions encompassed vision, rate of change, challenges, role of faculty, resources, enrolment, collaboration, responsibility for course design and content, mission and fate of the institution. The objective of this qualitative study was to sample the opinions of educational administrators and information technology specialists from selected US universities regarding the impact of e-learning on dental education to detect trends in their attitudes. Responses to the survey indicated disagreement between administrators and informational technology specialists regarding the rate of change, generation of resources, impact on enrolment, responsibility for course design and content, mission and fate of the university. General agreement was noted with regard to vision, challenges, role of faculty and need for collaboration.

Redefining reference in an academic health sciences library: planning for change

Deciding that changes in the pattern of questions at the reference desk required focused consideration, the reference librarians at the Health Sciences Library of the University at Buffalo held a planning retreat. Technology-induced changes in the information-seeking behavior and reference needs of the library's clientele caused a reassessment of how these needs could best be met and what is the best use of librarians' time. The librarians considered current trends in reference in other academic libraries, the specific needs of the clientele of the Health Sciences Library, and the strengths and expertise of the library staff. The results of this structured discussion produced ideas for redefining reference to provide customized services for the clients and environment.

Design and demonstration of an automated cell-based biosensor

Cell-based biosensors have the capacity to respond to a wide range of analytes in a physiologically relevant manner and appear well-suited for toxicity monitoring of both known and unknown analytes. One means of acquiring cellular functional information for biosensor applications involves extracellular recording from excitable cells, which can generate noninvasive and long-term measurements. Previous work from our laboratory described a prototype portable system capable of high signal-to-noise extracellular recordings, in spite of deficiencies in thermal control, fluidics handling, and absence of data acquisition (DAQ) capability. The present work describes a cell-based biosensor system that incorporates low noise amplifier and filter boards, a two-stage thermal control system with integrated fluidics and a flexible graphical user interface for DAQ and control implemented on a personal computer. Wherever possible, commercial off-the-shelf components have been utilized for system design and fabrication. The system exhibits input-referred noise levels of 5-10 microV(RMS), such that extracellular potentials exceeding 50-60 microV can be readily resolved. In addition, the biosensor system is capable of automated temperature and fluidics control. Flow rates can range from 0-2.5 ml/min, while the cell recording chamber temperature is maintained within a range of 36-37 degrees C. To demonstrate the capability of this system to resolve small extracellular potentials, recordings from embryonic chick cardiac myocytes have been performed.

Role of Campylobacter jejuni potential virulence genes in cecal colonization

Campylobacter jejuni, a common commensal in chickens, is one of the leading causes of bacterial gastroenteritis in humans worldwide. The aims of this investigation were twofold. First, we sought to determine whether mutations in the C. jejuni ciaB and pldA virulence-associated genes impaired the organism's ability to colonize chickens. Second, we sought to determine if inoculation of chicks with C. jejuni mutants could confer protection from subsequent challenge with the C. jejuni wild-type strain. The C. jejuni ciaB gene encodes a secreted protein necessary for the maximal invasion of C. jejuni into cultured epithelial cells, and the pldA gene encodes a protein with phospholipase activity. Also included in this study were two additional C. jejuni mutants, one harboring a mutation in cadF and the other in dnaJ, with which we have previously performed colonization studies. In contrast to results with the parental C. jejuni strain, viable organisms were not recovered from any of the chicks inoculated with the C. jejuni mutants. To determine if chicks inoculated with the C. jejuni mutants become resistant to colonization by the C. jejuni parental strain upon subsequent challenge, chicks were inoculated either intraperitoneally (i.p.) or both orally and i.p. with the C. jejuni mutants. Inoculated birds were then orally challenged with the parental strain. Inoculation with the C. jejuni mutants did not provide protection from subsequent challenge with the wild-type strain. In addition, neither the C. jejuni parental nor the mutant strains caused any apparent morbidity or mortality of the chicks. We conclude that mutations in genes cadF, dnaJ, pldA, and ciaB impair the ability of C. jejuni to colonize the cecum, that chicks tolerate massive inoculation with these mutant strains, and that such inoculations do not provide biologically significant protection against colonization by the parental strain.

Expression of the mRNA encoding truncated PPAR alpha does not correlate with hepatic insensitivity to peroxisome proliferators

Two alternatively spliced forms of human PPAR alpha mRNA, PPAR alpha1 and PPAR alpha2, have been identified. PPAR alpha1 mRNA gives rise to an active PPAR alpha protein while PPAR alpha2 mRNA gives rise to a form of PPAR which lacks the ligand-binding domain. PPAR alpha2 is unable to activate a peroxisome proliferator response element (PPRE) reporter gene construct in transient transfection assays. Both PPAR alpha1 and PPAR alpha2 mRNA are present in human liver, kidney, testes, heart, small intestine, and smooth muscle. In human liver, PPAR alpha2 mRNA abundance is approximately half that of PPAR alpha1 mRNA; a correlation analysis of PPAR alpha1 and PPAR alpha2 mRNA mass revealed an r-value of 0.75 (n = 18). Additional studies with intact liver from various species, showed that the PPAR alpha2/PPAR alpha1 mRNA ratios in rat, rabbit, and mouse liver were less than 0.10; significantly lower than the 0.3 and 0.5 ratios observed in monkey and human livers, respectively. To determine if a high PPAR alpha2/PPAR alpha1 mRNA ratio was associated with insensitivity to peroxisome proliferators, we treated human, rat, and rabbit hepatocytes with WY14643, a potent PPAR alpha activator, and measured acyl CoA oxidase (ACO) mRNA levels. Rat ACO mRNA levels increased markedly in response to WY14643 while human and rabbit hepatocytes were unresponsive. Thus, although the PPAR alpha2/PPAR alpha1 mRNA ratio is low in rabbits, this species is not responsive to peroxisome proliferators. Further studies with male and female rats, which vary significantly in their response to peroxisome proliferators, showed little difference in the ratio of PPAR alpha2/PPAR alpha1 mRNA. These data suggest that selective PPAR alpha2 mRNA expression is not the basis for differential species or gender responses to peroxisome proliferators.

Codon usage in the A/T-rich bacterium Campylobacter jejuni

Campylobacter jejuni is a Gram negative, microaerophilic pathogen that causes gastroenteritis in humans. The genome of C. jejuni is AT-rich, with a mol% G + C of 30.4. This high AT content was hypothesized to result in unique codon usage. In the present study, we analyzed the codon usage of sixty-seven C. jejuni genes and generated a codon frequency table. As predicted, the codon usage of C. jejuni revealed a strong bias towards codons ending in A or U. In addition to determining codon usage frequencies, the relative synonymous codon usage values were calculated to identify rare and optimal codons. Seventeen codons were identified as optimal and twelve codons as rare. Thirty-two codons exhibited little or no bias. A plot of the effective number of codons versus the third position %G + C values for the sixty-seven genes revealed that C. jejuni uses an average of 39 of the 61 codons to encode proteins. These data will be useful for various molecular analyses including selection of degenerate primers to screen C. jejuni-genomic DNA libraries.

Identification of the enteropathogens Campylobacter jejuni and Campylobacter coli based on the cadF virulence gene and its product

Campylobacter jejuni and Campylobacter coli are common causes of gastroenteritis in humans. Infection with C. jejuni or C. coli is commonly acquired by eating undercooked chicken. The goal of this study was to develop specific detection assays for C. jejuni and C. coli isolates based on the cadF virulence gene and its product. The cadF gene from C. jejuni and C. coli encodes a 37-kDa outer membrane protein that promotes the binding of these pathogens to intestinal epithelial cells. A fragment of approximately 400 bp was amplified from 38 of 40 (95%) C. jejuni isolates and 5 of 6 (83.3%) C. coli isolates with primers designed to amplify an internal fragment of the cadF gene. PCR was then used to amplify Campylobacter DNA from store-bought chickens. A 400-bp band was amplified from 26 of the 27 chicken carcasses tested by the PCR-based assay. The CadF protein was detected in every C. jejuni and C. coli isolate tested, as judged by immunoblot analysis with a rabbit anti-C. jejuni 37-kDa serum. In addition, methanol-fixed samples of whole-cell C. jejuni and C. coli were detected with the rabbit anti-37-kDa serum by using an indirect-immunofluorescence microscopy assay. These findings indicate that the cadF gene and its product are conserved among C. jejuni and C. coli isolates and that a PCR assay based on the cadF gene may be useful for the detection of Campylobacter organisms in food products.

Cloning, sequencing, and characterization of the lipopolysaccharide biosynthetic enzyme heptosyltransferase I gene (waaC) from Campylobacter jejuni and Campylobacter coli

Campylobacter jejuni and Campylobacter coli are common causes of gastrointestinal disease and a proportion of C. jejuni infections have been shown to be associated with the Guillain-Barré syndrome. The waaC gene from Campylobacter coli, involved in lipopolysaccharide core biosynthesis, was cloned by complementation of a heptose-deficient strain of Salmonella typhimurium, as judged by novobiocin sensitivity, lipopolysaccharide (LPS)-specific phage sensitivity, and polyacrylamide-resolved lipopolysaccharide profiles. The C. jejuni waaC gene was subsequently cloned using the waaC gene isolated from C. coli as a probe. The C. jejuni and C. coli waaC genes are capable of encoding proteins of 342 amino acids with calculated molecular masses of 39381Da and 39317Da, respectively. Sequence and in-vitro analyses suggested that the C. coli waaC gene may be transcribed from its own promoter. Translation of the C. coli waaC gene in a cell-free system yielded a protein with a Mr of 39000. The waaC gene was detected in every C. jejuni and C. coli isolate tested as judged by dot-blot hybridization analysis. Southern hybridization analysis indicated that both Campylobacter species contain a single copy of the waaC gene. Unlike Escherichia coli and S. typhimurium isolates, the waaC gene in C. jejuni and C. coli isolates does not appear to be linked to the waaF (rfaF) gene.

The Western New York Health Resources Project: developing access to local health information

The Western New York Health Resources Project was created to fill a gap in online access to local health information resources describing the health of a defined geographic area. The project sought to identify and describe information scattered among many institutions, agencies, and individuals, and to create a database that would be widely accessible. The project proceeded in three phases with initial phases supported by grant funding. This paper describes the database development and selection of content, and concludes that a national online network of local health data representing the various geographic regions of the United States would contribute to the quality of health care in general.

Development of cytochrome P450 17 alpha-hydroxylase (P450c17) mRNA and enzyme activity in neonatal ovaries of normal and hypogonadal (hpg) mice

The cytochrome P450 enzyme 17 alpha-hydroxylase (P450c17) is required for androgen synthesis and therefore regulates substrate supply for aromatization. In this study, changes in P450c17 activity and mRNA levels were measured during ovarian development in the normal mouse and in the hypogonadal (hpg) mouse which lacks circulating gonadotrophins. At birth, low levels of P450c17 activity and mRNA were detectable in normal ovaries. This basal level of expression did not change until after day 10 at which time both enzyme activity and mRNA levels increased by six- to eightfold. In the hpg mouse, levels of P450c17 mRNA were normal at birth but did not change significantly during subsequent development and were significantly less than normal by day 15. Results show that there is a low level of gonadotrophin-independent expression of P450c17 in the ovary at birth and that gonadotrophins are required for the subsequent increase in expression between days 10 and 15. In the ovary, P450c17 is expressed solely in the thecal/interstitial compartment and interstitial cells arise in the mouse ovary around day 11. Changes in P450c17 are likely, therefore, to be related to gonadotrophin-dependent development of the interstitial tissue in the mouse. Treatment of adult hpg mice with LH and FSH showed that both gonadotrophins can act to increase P450c17 activity. Since FSH acts only on the granulosa cell compartment of the ovary it is likely that FSH acts through a paracrine mechanism to regulate thecal/interstitial cell activity.

Optimising the removal of inhaled plutonium and americium from the rat by administration of ZnDTPA in drinking water

1. The efficacy of ZnDTPA administered in drinking water has been investigated for removing 238Pu and 241Am from the rat after their simultaneous inhalation as nitrates. 2. The continual administration of ZnDTPA 95 mumol kg-1 d-1 over a 21 d interval commencing 1 h after exposure reduced the 238Pu content of the lungs and total body to 2% and 8% of those in untreated animals; the corresponding values for 241Am were 3% and 5%. 3. The continual intakes of 950 mumol kg-1 d-1, intermittent intakes of 3600 mumol kg-1 d-1 and the repeated injection of 30 mumol kg-1 body weight were considered no more effective. 4. All orally administered concentrations of ZnDTPA, commencing 7 d after exposure, reduced the total body contents of 238Pu and 241Am to 17% and 20% of controls by 28 d. 5. Histopathological examination of the kidneys, liver and gastrointestinal tract showed no apparent effects of these treatment protocols. 6. It is concluded that the oral administration of ZnDTPA could be an effective treatment for the removal of inhaled transportable forms of Pu and Am after human exposure.

Development of cytochrome P450 aromatase mRNA levels and enzyme activity in ovaries of normal and hypogonadal (hpg) mice

The cytochrome P450 aromatase (P450arom) enzyme is required for bioconversion of androgen to oestrogen. In this study ovarian P450arom mRNA and enzyme activity have been measured during development in normal mice and hypogondal (hpg) mice which lack circulating gonadotrophins. A semi-quantitative reverse transcription-PCR (RT-PCR) technique was used to measure cytochrome P450arom mRNA levels and aromatase enzyme activity was measured directly. Using RT-PCR, P450arom mRNA was detectable in the adult mouse ovary and also in the uterus, kidney, brain and skeletal muscle but not in cardiac smooth muscle. In the normal mouse, P450arom mRNA was detectable in the ovary on the day of birth (day 1) and levels increased significantly up to day 15 with the most marked changes seen between days 1 and 5. Aromatase activity was also detectable at all ages in the ovary and increased significantly between days 1 and 7. In ovaries from hpg mice, normal levels of P450arom mRNA were present on day 1 but there was no significant change in P450arom mRNA at later ages up to day 15. These results show that in the newborn mouse ovary, which contains only primordial follicles, there is a basal expression of P450arom mRNA which is not gonadotrophin-dependent. After 1 day, however, gonadotrophins are required for normal expression of ovarian P450arom and this coincides with development of primary and secondary follicles.

Gonadotropin-dependent and gonadotropin-independent development of inhibin subunit messenger ribonucleic acid levels in the mouse ovary

The inhibins and activins are dimeric growth factors with important regulatory functions during development. In this study, changes in inhibin subunit messenger RNA (mRNA) levels were measured in the ovary during early postnatal development in the normal mouse and the hypogonadal (hpg) mouse, which lacks circulating gonadotropins. Levels of inhibin alpha-, beta A-, and beta B-subunit mRNAs were measured relative to beta-actin using a semiquantitative reverse transcription-polymerase chain reaction technique. Transcripts encoding all three subunits were present at birth; the alpha-subunit was the most abundant, followed by beta A-subunit (6% of alpha) and beta B-subunit (0.4% of alpha). After birth, levels of all three subunit transcripts increased between 6- and 10-fold. Changes in inhibin beta A- and beta B-subunit levels were most marked around 7 days, the period of secondary follicle development, whereas alpha-subunit transcript levels increased constantly after day 1 to reach a peak at 10 days, when mature secondary follicles are present. In hpg mice, levels of ovarian inhibin alpha-subunit mRNA levels were normal at all ages up to 15 days. In contrast, inhibin beta A-subunit mRNA levels were normal at birth in hpg mice, but did not increase after that up to day 15. Levels of beta B-subunit mRNA were significantly lower than normal on day 1 in hpg mice and also failed to show a significant increase up to 15 days. These results show that inhibin subunit mRNA levels are differentially regulated during ovarian development in the mouse. Normal expression of beta-subunits is completely gonadotropin dependent around the period of late primary to secondary follicle development. The inhibin alpha-subunit, in contrast, is expressed at a high level during development independent of gonadotropin stimulation.

Decorporation of thorium-228 from the rat by 3,4,3-LIHOPO and DTPA after simulated wound contamination

1. With DTPA as a comparison, the siderophore analogue 3,4,3-LIHOPO has been examined for its ability to remove 228Th nitrate from the rat after subcutaneous (sc) and intramuscular (im) injection to simulate wound contamination. The commencement of treatment was delayed 30 min, 6 h or 1 d and the animals killed at 7 d. 2. In all cases 3,4,3-LIHOPO was appreciably more effective than DTPA although the efficacy of treatment and the relative effectiveness of the ligands decreased rapidly with their delay in administration. 3. Optimum removal with both ligands occurred when initial local administration at 30 min after exposure was followed by repeated intraperitoneal injection at 6 h, 1, 2 and 3 d. Under these conditions the body content of 228Th was reduced to 20% of controls after sc injection and 15% after im injection. The corresponding values using repeated DTPA administration were 80% and 54%. 4. It is concluded that 3,4,3-LIHOPO represents, potentially, a considerable advance on DTPA, the current agent of choice for the treatment of wounds contaminated by 228Th.

Comparative efficacies of 3,4,3-LIHOPO and DTPA for enhancing the excretion of plutonium and americium from the rat after simulated wound contamination as nitrates

With DTPA as a comparison, the siderophore analogue 3,4,3-LIHOPO has been examined for its ability to remove 238Pu and 241Am from the rat after subcutaneous (s.c.) and intramuscular (i.m.) injection of about 200 Bq of each actinide (0.3 ng Pu, 1.6 ng Am). After the s.c. deposition of 238Pu and 241Am, both ligands were more effective after local administration than (in decreasing order) their repeated interperitoneal (i.p.) injection, single i.p. injection and continuous infusion. Dosages of 3 mumol kg-1 of 3,4,3-LIHOPO were at least as effective as 30 mumol kg-1 DTPA after each mode of administration. The most effective regimen of those investigated for s.c. 238Pu and 241Am involved local administration of 30 mumol kg-1 of 3,4,3-LIHOPO at 30 min followed by i.p. injections at 6 h, 1, 2 and 3 day. By day 7 after exposure, the amounts of 238Pu and 241Am retained in the body were 2 and 7% of those in controls, respectively and 10 and four times less than when DTPA was administered using the same regimen. The ligand 3,4,3-LIHOPO was more effective for 238Pu and 241Am after their i.m. injection. This was attributed to the greater retention of these actinides at the wound site (97 versus 67%) when treatment commenced. After a single local injection of 30 mumol kg-1 at 30 min, the amounts of 238Pu and 241Am retained in the body at 7 day were 0.9 and 0.8% of controls. These values were 34 and 27 times less than after local and repeated i.p. injections of DTPA at dosages of 30 mumol kg-1. It is concluded that the administration of 3,4,3-LIHOPO represents potentially a most significant advance in the treatment of wound contamination by 238Pu and 241Am by chelating agents.

Removal of inhaled plutonium and americium from the rat by administration of ZnDTPA in drinking water

This study has examined the efficacy of ZnDTPA administered in drinking water for removing 238Pu and 241Am from the rat after their simultaneous inhalation as nitrates; the dosage used was 95 mumol kg-1d-1. The continuous administration of ZnDTPA over a 14 d interval, commencing 1 h after exposure, reduced the lung and total body contents of 238Pu to, respectively, 11% and 18% of those in untreated rats; the corresponding values for 241Am were 11% and 14%. After the continuous administration of 95 mumol kg-1 from 4 d to 28 d post exposure, the lung and total body contents of 238Pu were, respectively, 5% and 16% of those in controls; the corresponding values for 241Am were 7% and 19%. Further reductions in the actinide contents of body tissues were found when treatment was extended to 52 d or 76 d. These regimens were as effective as twice weekly injections of 30 mumol kg-1 ZnDTPA commencing at 4 d. After the continuous administration of 95 mumol kg-1 d-1 for 72 d, some pathological changes to the gastrointestinal tract were observed but these were considered to be reparable. It was concluded that further work is required to evaluate the toxicity of the ligand and to establish the optimal treatment regimen.

The United Kingdom Heart Valve Registry

The United Kingdom Heart Valve Registry project began in 1986 following discussions between the Department of Health (DOH) and the Society of Cardiothoracic Surgeons of the United Kingdom and Ireland. The intention was to establish a computerized database for valve replacement operations carried out in the UK Health Service cardiac units. This paper describes the experience gained over the first five years of this project. Around 30,000 patients were entered in the registry between 1986 and 1990. All Uk Health Service cardiac surgical units contribute their data, which is processed by the central Registry Office. The accuracy of the mortality data is ensured by tracking the registered patients through the Office of Population Census and Surveys (OPCS). The pattern of valve replacement surgery over the period 1986-90 revealed several interesting trends. Although the number of procedures remained static at around 5,000 valve transplants per year, the number of aortic replacements increased and the number of mitrals decreased. The use of prosthetic valves increased from 54% in 1986 to over 70% in 1990. The mean age of the patients increased from 58.31 years in 1986 to 60.97 years in 1990, with over 22% of the valve replacement operations in 1990 being performed on patients over 70 years of age. The five year survival rate for patients over 70 years at the time of the valve implant is significantly lower than for patients under 70 years (p < 0.005).

Efficacy of tiron for enhancing the excretion of uranium from the rat

Tiron (sodium 4,5-dihydroxybenzene-1,3-disulphonate) has been suggested as a possible antidote for acute uranium poisoning. In this study, the compound has been administered intraperitoneally to rats in dosages of 30, 300 or 1000 mumols kg-1 at 20, 60 and 180 min after the intratracheal instillation of uranyl nitrate. The amounts of uranium deposited in the lungs of rats were equivalent to intakes by workers of about 12 times the permitted daily limit of 2.5 mg. The average body content of uranium at 5 d after exposure were, respectively, about 100%, 78% and 65% of those in untreated animals. It is concluded that the administration of Tiron is of limited practical value for treatment of uranium exposures not greatly in excess of the permitted intake.

The efficacy of DFO-HOPO, DTPA-DX and DTPA for enhancing the excretion of plutonium and ameriicum from the rat

A hydroxypridinone derivative of desferrioxamine (Na-DFO-HOPO), a dihydroxamic derivative of diethylenetriaminepenta-acetic acid (ZnNa-DTPA-DX), and DTPA (CaNa3- and ZnNa3-DTPA) were tested at dosages of 30 mumol kg-1 for their ability to remove 238Pu or 241Am from rats after their intravenous injection as citrate or inhalation as nitrate. The most effective treatment regimen for injected Pu was the repeated administration of DFO-HOPO; by 7 days the body content was reduced to 8% of that in untreated animals. Repeated dosages of 3 mumol kg-1 DFO-HOPO were as effective as those of 30 mumol kg-1 DTPA. After inhalation of Pu nitrate, repeated treatment with DTPA, DTPA-DX or DFO-HOPO reduced the body content by 7 days to, respectively, 10, 15 and 31% of those in untreated animals. After inhalation of Am, DTPA-DX and DTPA were equally effective, the body contents being reduced to 7% of control values with repeated treatment. Injection of DFO-HOPO was ineffective for enhancing the elimination of inhaled or injected Am. The results confirm the strategy of examining the use of siderophore analogues for the decorporation of Pu or Am. However, at present DTPA should remain the agent of choice, particularly after inhalation.

The efficacy of DTPA treatment after deposition of thorium nitrate in the rat lung

The efficacy of CaDTPA and ZnDTPA, the chelating agents of choice for several actinide elements, have been evaluated after the deposition of thorium in the rat lung in widely different amounts. The results showed that: 1. When the initial mass concentration of thorium simulated human exposure to four times the annual limits on intake for 232Th, the prompt (300 or 1000 mumol kg-1 body weight at 0.02 d) or repeated (30 or 300 mumol kg-1 body weight at 0.02, 0.25, 1,2,3 d) administration of CaDTPA were at best only moderately successful for enhancing the elimination of thorium. By 7 d after exposure, the body contents of thorium were, respectively, about 74%, 65%, 90% and 74% of those present in untreated animals. 2. When the mass concentration simulated 1.7 x 10(-3) times the annual limits on intake for 232Th, the efficacy of treatment was not increased appreciably despite the substantial reduction in mass. After the repeated administration of CaDTPA at doses of 30 and 300 mumol kg-1 using the protocol above, the body contents of thorium by 7 d were, respectively, 69% and 51% of those in untreated animals. 3. Under comparable conditions, the efficacy of ZnDTPA was less than CaDTPA. The results suggest that more effective chelating agents are needed for the treatment of workers exposed to water soluble thorium compounds.

The efficacies of pure LICAM(C) and DTPA on the retention of plutonium-238 and americium-241 in rats after their inhalation as nitrate and intravenous injection as citrate

The pure carboxylated catechoyl amide LICAM(C) and the calcium and zinc salts of diethylenetriaminepenta-acetic acid (DTPA), were tested for efficacy for removing 238Pu and 241Am from rats after inhalation of the nitrate or intravenous injection of the citrate. The results were compared with the efficacy of methylated LICAM(C) used in previous experiments. It was shown that: (1) after inhalation of 238Pu nitrate, DTPA was far superior to pure LICAM(C); (2) after intravenous injection of 238Pu citrate, the infusion of DTPA plus LICAM(C) was only marginally more effective than DTPA alone; and (3) after inhalation or intravenous injection of 238Pu plus 241Am, the efficacy of pure LICAM(C) was only marginally more effective than the methylated form and neither form was effective for the decorporation of 241Am. It was concluded that DTPA, at present, remains the chelating agent of choice for treating persons accidentally contaminated with transportable forms of Pu and Am.

The efficacies of pure LICAM(C) and DTPA for enhancing the elimination of plutonium-238 and americium-241 from rats after their inhalation as nitrate

After the inhalation of 238Pu and 241Am as nitrate, the repeated administration of DTPA is far superior to that of LICAM(C) for enhancing their elimination from the body. The therapeutic efficacies of these chelating agents are however similar after intravenous injection of 238Pu as citrate. It is concluded that DTPA should remain the agent of choice for treating persons contaminated internally with transportable forms of these actinides.

The metabolic behaviour of uranium octoxide bearing residues after their deposition in the rat lung: the implications for occupational exposure

This paper describes the metabolic behaviour in rats of uranium inhaled as a U3O8 bearing residue. The biokinetic behaviour of uranium in workers has been predicted by combining the transfer rates to blood in rats with mucociliary clearance rates obtained from human volunteers exposed to other aerosols. It is concluded that chest monitoring will be of value for assessing acute and chronic intakes of the residue below the proposed annual limit (6 x 10(3) Bq) whilst urinary excretion data should be interpreted with caution.

The metabolism of ceramic and non-ceramic forms of uranium dioxide after deposition in the rat lung

Ceramic and non-ceramic forms of uranium dioxide, produced industrially, were administered to rats either by inhalation or as an aqueous suspension which was injected directly into the pulmonary region of the lungs. The results showed that: 1 both materials should be assigned to inhalation class Y as defined by the International Commission on Radiological Protection; 2 whilst the translocation of uranium to the blood for the non-ceramic UO2 was about twice that obtained for the ceramic form, the two dioxides were unlikely to be differentiated on the basis of their lung retention kinetics; 3 the distribution of uranium amongst body tissues and the relationship between systemic content and cumulative urinary excretion indicated that it was transported in the hexavalent form; 4 in addition to air sampling procedures, lung radioactivity counting measurements could be used to advantage for assessing occupational exposures; 5 the exposure limits should be based on radiation dose rather than chemical toxicity.

Studies on the metabolic behaviour of industrial actinide-bearing aerosols after deposition in the rat lung: an experimental basis for interpreting chest monitoring data and assessing limits on intake for workers

The metabolism of 239Pu and 241Am in 3 site-specific industrial dusts has been studied after their deposition in the rat lung. A comparative experiment has also been carried out with a mixture of these actinides inhaled as their nitrates. The aim of this study was to provide an experimental basis for assessing limits on intake and to establish whether the 239Pu content in the lungs could be interpolated from measurements of 241Am.

THE RESULTS

1 demonstrate the wide differences in the lung retention kinetics of the actinides and in the absolute and relative amounts translocated to the blood that can occur for industrially produced materials; 2 show that the annual limits on intake (ALIs) for the different materials vary between those postulated for class W and Y compounds by the International Commission on Radiological Protection; 3 indicate that acute intakes of 239Pu equivalent to the ALI can, depending on the nature of the dust, be estimated from 241Am chest monitoring data at times from a few days up to about 3 years after exposure.

Metabolism of uranium in the rat after inhalation of two industrial forms of ore concentrate: the implications for occupational exposure

Aerosols produced from two commercially available ore concentrates in which the uranium was present essentially in the one as ammonium diuranate (ADU) and in the other as uranium octoxide (U3O8) were administered to rats. The results show that: 1 uranium in the ADU bearing material was cleared rapidly from the lungs, mainly to the blood, such that the retention kinetics were similar to those for a class D (highly transportable) compound as defined by ICRP; 2 uranium in the U3O8 bearing material was removed from the lungs principally by mechanical processes, the retention kinetics in this case being similar to those defined for a class Y (poorly transportable) compound; 3 for both materials the distribution of uranium amongst body tissues and the fraction of the systemic content excreted in urine were similar to those obtained after the injection of soluble hexavalent compounds; 4 for workers potentially exposed to both these materials, urine monitoring and lung radioactivity counting measurements should be used in addition to air sampling procedures for assessing the intake of uranium. 5 intakes of the ADU bearing material should be restricted to those permitted for short-term exposures on the basis of chemical toxicity, whereas those for the U3O8 bearing material should be governed by radiation dose.

Efficacies of LICAM(C) and DTPA for the decorporation of inhaled transportable forms of plutonium and americium from the rat

The efficacies of N1, N5, N10, N14-tetrakis (2,3-dihydroxy-4-carboxybenzoyl)-tetra-azatetradecane [LICAM(C)] and diethylenetriaminepenta-acetic acid (DTPA) (30 mumol/kg body wt.) have been investigated for plutonium (Pu) decorporation after inhalation as the nitrate or tributyl phosphate (TBP) complexes and the data compared with those obtained after its intravenous injection as the citrate. The efficacy of removal of americium (Am) inhaled as the nitrate has also been examined. The results show that: whereas LICAM(C) and DTPA were similarly effective for removing Pu from the blood, LICAM(C) was considerably inferior to DTPA when transportable forms of Pu were inhaled; LICAM(C) is ineffective for the decorporation of Am; the optimum treatment regimen for both Pu and Am involved the prompt and repeated administration of DTPA.

Use of DTPA for increasing the rate of elimination of plutonium-238 and americium-241 from rodents after their inhalation as the nitrates

This study has shown that: both inhaled (2 mumol/kg) and injected (30 mumol/kg) diethylenetriaminepenta-acetic acid (DTPA) can reduce the lung deposit of 238 Pu and 241 Am inhaled as nitrate to about 1% of that in untreated controls; injection of DTPA is more effective than aerosolized DTPA for reducing deposits of 238Pu and 241Am in the liver and skeleton; combined treatment involving early inhalation of DTPA followed by repeated intravenous injections is likely to be the most effective treatment for workers who have accidentally inhaled plutonium and americium nitrates.