Enhanced kinetic stability of [Pd2L4]4+ cages through ligand substitution

[Pd₂(tripy)₄]⁴⁺ cage architectures (where tripy = 2,6-bis(pyridin-3-ylethynyl)pyridine) were made more kinetically robust in the presence of range of nucleophiles by the addition of amino groups in either the 2-(2A-tripy) or 3-(3A-tripy) positions of the tripy ligands' terminal pyridines, with the [Pd₂(2A-tripy)₄]⁴⁺ cage proving the most stable.

Parameter Estimation and Energy Minimization for Region-Based Semantic Segmentation

We consider the problem of parameter estimation and energy minimization for a region-based semantic segmentation model. The model divides the pixels of an image into non-overlapping connected regions, each of which is to a semantic class. In the context of energy minimization, the main problem we face is the large number of putative pixel-to-region assignments. We address this problem by designing an accurate linear programming based approach for selecting the best set of regions from a large dictionary. The dictionary is constructed by merging and intersecting segments obtained from multiple bottom-up over-segmentations. The linear program is solved efficiently using dual decomposition. In the context of parameter estimation, the main problem we face is the lack of fully supervised data. We address this issue by developing a principled framework for parameter estimation using diverse data. More precisely, we propose a latent structural support vector machine formulation, where the latent variables model any missing information in the human annotation. Of particular interest to us are three types of annotations: (i) images segmented using generic foreground or background classes; (ii) images with bounding boxes specified for objects; and (iii) images labeled to indicate the presence of a class. Using large, publicly available datasets we show that our methods are able to significantly improve the accuracy of the region-based model.

Biologically active [Pd2L4](4+) quadruply-stranded helicates: stability and cytotoxicity

There is emerging interest in the anti-proliferative effects of metallosupramolecular systems due to the different size and shape of these metallo-architectures compared to traditional small molecule drugs. Palladium(II)-containing systems are the most abundant class of metallosupramolecular complexes, yet their biological activity has hardly been examined. Here a small series of [Pd2(L)4](BF4)4 quadruply-stranded, dipalladium(II) architectures were screened for their cytotoxic effects against three cancer cell lines and one non-malignant line. The helicates exhibited a range of cytotoxic properties, with the most cytotoxic complex [Pd2(hextrz)4](BF4)4 possessing low micromolar IC50 values against all of the cell lines tested, while the other helicates displayed moderate or no cytotoxicity. Against the MDA-MB-231 cell line, which is resistant to platinum-based drugs, [Pd2(hextrz)4](BF4)4 was 7-fold more active than cisplatin. Preliminary mechanistic studies indicate that the [Pd2(hextrz)4](BF4)4 helicate does not induce cell death in the same way as clinically used metal complexes such as cisplatin. Rather than interacting with DNA, the helicate appears to disrupt the cell membrane. These studies represent the first biological characterisation of quadruply-stranded helicate architectures, and provide insight into the design requirements for the development of biologically active and stable palladium(II)-containing metallosupramolecular architectures.

Chloride triggered reversible switching from a metallosupramolecular [Pd2L4]4+ cage to a [Pd2L2Cl4] metallo-macrocycle with release of endo- and exo-hedrally bound guests

A metallosupramolecular [Pd₂L₄]⁴⁺ cage can be cleanly, and reversibly, converted into a [Pd₂L₂Cl₄] metallo-macrocycle upon addition or removal of chloride ions.

Diversity of 16S rRNA gene, ITS region and aclB gene of the Aquificales

The Aquificales are prevalent members of the microbial communities inhabiting many marine and terrestrial hydrothermal systems. Numerous new strains were obtained from deep-sea and terrestrial hydrothermal systems. In order to resolve the phylogenetic relationships within this group, three different phylogenetic datasets were used, namely the 16S rRNA gene, the intergenic transcribed spacer region between the 16S rRNA and 23S rRNA genes (ITS) and the gene coding for the ATP citrate lyase (aclB), a key enzyme in the reductive TCA cycle. The data were analyzed using neighbor-joining, parsimony and maximum likelihood. The resulting phylogenies appeared to be consistent between the three markers. The three genes confirmed the presence of isolates that merit further characterization and descriptions as new species and perhaps even new genera. The detailed phylogenetic interrelationships of these isolates are described here.

Heavy metal contamination of water, soil and produce within riverine communities of the Río Pilcomayo basin, Bolivia

The Río Pilcomayo heads on the Cerro Rico de Potosí precious metal-polymetallic tin deposits of Southern Bolivia. Mining of the Potosí deposits began in 1545 and has led to the severe contamination of the Pilcomayo's water and sediments for at least 200 km downstream of the mines. This investigation addresses the potential human health affects of metal and As contamination on four communities located along the upper Río Pilcomayo by examining the potential significance of human exposure pathways associated with soils, crops and water (including river, irrigation and drinking water supplies). The most significantly contaminated agricultural soils occur upstream at Mondragón where Cd, Pb and Zn concentrations exceed recommended guideline values for agricultural use. Further downstream the degree of contamination decreases, and metal concentrations are below Dutch, German and Canadian guideline values. Metal and As concentrations in agricultural products from the four communities were generally below existing guidelines for heavy metal content in commercially-sold vegetables. Thus, the consumption of contaminated produce does not appear to represent a significant exposure pathway. A possible exception is Pb in carrots, lettuce and beetroots from Sotomayor and Tuero Chico; 37% and 55% of the samples, respectively, exceeded recommended guidelines. Most communities obtain drinking water from sources other than the Río Pilcomayo. In general, dissolved concentrations of metals and As in drinking water from the four studied communities are below the WHO guideline values with the exception of Sb, which was high at Tasapampa. The inadvertent ingestion of contaminated water from irrigation canals and the Río Pilcomayo represents a potential exposure pathway, but its significance is thought to be minimal. Given the degree of soil contamination in the area, perhaps the most significant exposure pathway is the ingestion of contaminated soil particles, particularly particles attached to, and consumed with vegetables. The risks associated with this pathway can be reduced by thoroughly washing or peeling the vegetables prior to consumption. Other exposure pathways that are currently under investigation include the consumption of contaminated meat from livestock and poultry, which drink polluted waters and the ingestion of contaminated wind-blown dust.

[Medical and biological consequences of human's chronic exposure to radiation]

The authors considered medical consequences of radiation accidents (burial of radioactive waste into Techa river and accident in 1957) in "Majak" Industrial Association. Results of long-term observations helped to evaluate health state of people who underwent chronic exposure to radiation and of their descendants.

Fatal chemotherapy-induced encephalopathy following high-dose therapy for metastatic breast cancer: a case report and review of the literature

Chemotherapy-induced encephalopathies occur in a variety of clinical settings and the most detailed accounts have been described following combination methotrexate and radiation therapy. The case described herein developed severe encephalopathy following a high-dose chemotherapy protocol used in the treatment of metastatic carcinoma of the breast. Visual symptoms developed 3 weeks after completing high-dose chemotherapy and peripheral blood hematopoietic stem cell transplantation. Over the next several weeks, additional neurologic deficits developed and continued to progress despite various treatment interventions. Diffuse deep gray matter damage was identified on MR imaging and a brain biopsy revealed pathological findings similar in many respects to those described for methotrexate/radiation, cisplatin, BCNU and/or 5 FU/levamisole-related leukoencephalopathy. The patient succumbed to complications resulting from the CNS disorder, 8 weeks after the onset of symptoms. This case is unusual for two reasons. First, the patient developed severe encephalopathy following a high-dose chemotherapy protocol commonly used in the treatment of metastatic breast carcinoma and second, the encephalopathy involved primarily deep gray matter structures rather than white matter.

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Stable chromosome aberrations in atomic bomb survivors: results from 25 years of investigation

Frequencies of stable chromosome aberrations from more than 3,000 atomic bomb survivors were used to examine the nature of the radiation dose response. The end point was the proportion of cells with at least one translocation or inversion detected in Giemsa-stained cultures of approximately 100 lymphocytes per person. The statistical methods allow for both imprecision of individual dose estimates and extra-binomial variation. A highly significant and nonlinear dose response was seen. The shape of the dose response was concave upward for doses below 1.5 Sv but exhibited some leveling off at higher doses. This curvature was similar for the two cities, with a crossover dose (i.e. the ratio of the linear coefficient to the quadratic coefficient) of 1.7 Sv (95% CI 0.9, 4). The low-dose slopes for the two cities differed significantly: 6.6% per Sv (95% CI 5.5, 8.4) in Hiroshima and 3.7% (95% CI 2.6, 4.9) in Nagasaki. This difference was reduced considerably, but not eliminated, when the comparison was limited to people who were exposed in houses or tenements. Nagasaki survivors exposed in factories, as well as people in either city who were outside with little or no shielding, had a lower dose response than those exposed in houses. This suggests that doses for Nagasaki factory worker survivors may be overestimated by the DS86, apparently by about 60%. Even though factory workers constitute about 20% of Nagasaki survivors with dose estimates in the range of 0.5 to 2 Sv, calculations indicate that the dosimetry problems for these people have little impact on cancer risk estimates for Nagasaki.

The NHS manager. A view from the bridge

The changing role of the manager has been a growing area of both academic and popular literature over recent years. In addition, the interest of the popular press has made terms like "grey suit" and "fat cat" common terminology. Management roles and managerial authority within today's organisations have seen many changes. This has led to frustration and anxiety for managers as they have watched their role change. In the NHS, like other sectors, managers have become a target for organisational redundancies and have experienced increased responsibility, closer monitoring of performance and heightened job insecurity. This paper aims to offer a contribution to the empirical data on managers by investigating one group of NHS managers' own perceptions of how others see their role. The findings suggest that NHS managers are very aware of the largely negative perceptions that surround them but accept this as an integral part of their role.

Bringing Canadian healthcare closer to home: the initial stages of change for senior managers within the province of British Columbia

This paper explores some recent healthcare reforms within the Canadian healthcare sector. As in most countries across the world, healthcare managers in Canada have been faced with the dilemma of how to achieve a balance between equity of provision and expenditure control. This study explores the external and internal pressures for change at the provincial and national levels within Canada. More significantly, it focuses on how the early stages of these changes have resulted in altered work roles and relationships for healthcare managers. A case study of British Columbia is described, where radical changes occurred in the healthcare sector in the mid-1990s. Interviews conducted with a sample of senior healthcare managers in the province illustrate how the restructuring of healthcare impacted upon management roles, structures and communication. The qualitative interview data is intended to provide an important addition to the body of largely quantitative, statistical data that is collected on international health systems on a regular basis. How the findings of the case study can contribute to learning and practice within the health services management arena is discussed.

Treatment of posttraumatic ocular dysmotility using autogenous buccal fat grafts in a porcine model

Diplopia occurring after orbital trauma is a complex and difficult clinical problem. Numerous potential mechanisms exist by which it may occur. Restrictive ocular dysmotility caused by intraorbital scarring is a major component in diplopia's pathogenesis. The current large animal study was conducted to develop an experimental model of restrictive ocular dysmotility that would quantitatively characterize the biomechanical properties of the globe rotations. Using this model, a novel method of restoring the low-friction milieu within the orbit by interposing a buccal fat graft was tested. In the initial stage, the baseline force duction was measured in 20 pig eyes using a highly sensitive, digital tensiometer. Traumatic violation of Tenon's fascia with electrocautery into the extraconal fat and the periorbita was followed by direct suturing of the extraocular muscle to the nearest orbital periosteum. After 6 weeks, the measurements (again in the field of the traumatized muscle) were repeated, and the eyes were divided into two treatment groups (n = 10 eyes per group). The left eye received the standard lysis of adhesion, whereas the right eye received lysis and buccal fat interposition grafting. The third and final force measurements were performed 6 weeks after treatment. The results showed a baseline linear load-displacement curve of 0 to 8 mm, with the globe rotating 400 microm for every 1000 mg of tensile load. Surgical trauma increased the slope as defined by load/displacement but, surprisingly, the relationship remained linear in the entire range from 2 to 8 mm. This linear relationship was seen in all stages: baseline, after trauma to Tenon's fascia, after surgical lysis alone, and after lysis with buccal fat interposition. The difference was in the slope, or stiffness. Lysis alone partially reduced the slope, but it was still higher than baseline. Lysis and buccal fat grafting returned the slope to near baseline. This, however, did not reach the level of statistical significance. It seems that a focal intervention along the course of an extraocular muscle altered the composite behavior of orbital resistance to globe rotation. Although buccal fat grafting did not significantly improve motility, it did not worsen it.

Quantitative forced ductions in an animal model--characterization of passive forces

PURPOSE

Our purpose was to characterize the passive tissue forces involved in ocular rotation in a controlled animal model and to evaluate the influence of manual versus mechanized ductions, repeated measurements, speed of rotation, and the influence of the nondepolarizing muscle relaxant mivacurium.

METHODS

Forced ductions were performed under general anesthesia on 20 eyes of 10 pigs, with or without mivacurium, with use of a highly sensitive force gauge attached to the eye by a traction suture. The eye was moved either manually or at constant speed with a motorized platform. Eyes were rotated a total of 8 mm from their resting position under anesthesia. The force-displacement relationship was analyzed and compared between groups.

RESULTS

A linear (elastic) relationship between force and displacement was noted, with a slope of 0.4 g per degree with use of the mechanized technique. Neither speed of rotation, use of mivacurium, nor repeated ductions significantly influenced the shape or slope of the relationship. Hysteresis averaged 2 to 4 g. Measurements performed with use of the motorized platform showed significantly improved reliability over those made manually.

CONCLUSIONS

The passive length-tension data correlate well with data reported by others in humans. Within a wide range of eye movement, this force is elastic in nature. For relatively low angular velocities, such as might be produced in smooth pursuit, the passive forces do not change appreciably with changes in velocity. The nondepolarizing muscle relaxant mivacurium has no effect on accurate performance of passive forced ductions under general anesthesia. Studies collecting quantitative data on passive orbital forces should be performed, when feasible, with an automated duction and recording apparatus.

Restricted ocular motility after orbital trauma--studies with an animal model

OBJECTIVE

Our purpose was to develop a quantitative model of restricted ocular motility (fat adherence syndrome) in the pig orbit to facilitate research into pathogenesis and treatment.

METHODS

Twenty eyes of 10 pigs were used in an attempt to create a fibrous adhesion between either the inferior rectus or the medial rectus muscle and the adjacent periorbita. Quantitative forced ductions were performed preoperatively and 6 weeks postoperatively with an electronic force gauge.

RESULTS

Forced ductions displayed a linear relationship to displacement over the range tested, both preoperatively and postoperatively. Although increased resistance to forced ductions was produced in 10 of the 20 (50%) eyes, the average changes were not statistically significant. The absolute change in force (Postoperative--Preoperative) was linearly related to the amount of ocular rotation. Reproducibility of measurements was markedly improved by the use of a motorized forced duction apparatus compared with manual rotation.

CONCLUSIONS

The results from this study, and those from previous work, suggest that the classic fat adherence syndrome is an uncommon event, even after significant soft tissue injury in the orbit. Further studies are needed to more completely define the risk factors and pathogenesis of the fat adherence syndrome and the suitability of the pig orbit as a model.

Doctor in the process. The engagement of clinical directors in hospital management

Aims to examine medical involvement in hospital management processes, and to consider the implications of current experience for the next generation of clinical directors. Doctors who move into a formal management role often find themselves unprepared for their new responsibilities. Research has thus concentrated on identifying the management competences which doctors lack, and with designing ways to remedy the deficit. Seeks to move beyond this deficit model by adopting a perspective which focuses on the engagement of doctors in the management process. Draws data from in-depth interviews with six clinical directors and 19 other members of the hospital management team at Leicester General Hospital NHS Trust (LGH). Content analysis of interviews suggest that the engagement of clinical directors in the hospital management process at this site can be described as reluctant, transient, service-driven, power-pulled and pressured. This negative portrayal of the role, however, must be set in the context of the "management expectation" held of clinical directors by other hospital managers and staff--an expectation that is not currently fulfilled.

The importance of being earnest: reflections on an attempt to create an information-led organizational culture in the NHS

Presents a study of organizational culture in a community health-care Trust in the UK. The Trust has been involved in attempting to create what was described as an information-led culture and is concurrent with the implementation of a new information system. Describes some of the recent management initiatives which were intended to improve communications within the Trust and to provide employees with a better understanding of the changes which have been taking place. Identifies findings which suggest that there was some distance between the perceptions of management and those of employees. While the senior management team appear to have been in earnest in attempting to ensure that staff have the information and understanding they need, the results of an organizational culture survey suggest that these efforts may have been ineffective.

Communications between professional groups in an NHS trust hospital

Discusses an audit of communications between doctors and other professional groups in a National Health Services trust hospital. The project was undertaken as a result of senior management's perception that there were problems regarding the interface between professionals and junior doctors particularly, and that these have a potentially detrimental impact on patient care. The aim of the study was to improve the work environment of medical practitioners and professional staff by researching the factors affecting communication and the sources of conflict which exist between the groups. Describes the methodology and provides an overview of the main findings grouped into themes. A large number of recommendations for change have been made to the hospital concerning systems, procedures, structures, training and inter-professional boundaries. Implementation of some of these recommendations has taken place already. Full evaluation of their impact is yet to be determined.

Cancer risks and biomarker studies in the atomic bomb survivors

This paper describes recent studies on cancer incidence among Japanese atomic bomb survivors. The report includes a brief description of the primary atomic bomb survivor cohorts. The results illustrate the magnitude of the excess risks and show how these risks vary with sex, age at exposure and time. Descriptions are presented in terms of both excess relative risks and excess absolute rates. The paper also includes a summary of the current status of research on biomarkers of radiation exposure in the atomic bomb survivors.

Stable chromosome aberrations among A-bomb survivors: an update

Analysis of data on stable chromosome aberrations collected between 1968 and 1985 by the Radiation Effects Research Foundation (RERF) on 1703 individuals exposed to A-bomb radiation in Hiroshima and Nagasaki, Japan, reveals different dose-response relationships in the two cities, as well as significant effects of both time of assay and age at exposure. In Hiroshima, the proportion of cells with aberrations increased by 0.080 per sievert at low doses, assuming a constant neutron radiation RBE of 10 relative to gamma radiation, for assays performed during the latest period (1981-1985). In Nagasaki, the low-dose increase was 0.0126 per sievert. There was evidence that radiation exposure was more effective for producing stable aberrations at some younger ages at exposure, although the interpretation of this interaction is difficult. Modeling neutron and gamma-ray components of dose separately in a way which allows the neutron RBE to vary with dose yielded an estimated low-dose limiting value of RBE of 707 (95% confidence bound 200-infinity), with a low-dose response of approximately 0.008 aberrations per sievert. This RBE is much higher than the published RBEs for induction of aberrations in vitro. The high estimated RBE and the differences in dose response by city both are suggestive of systematic dose estimation errors in which either neutrons were underestimated in Hiroshima or gamma rays were overestimated in Nagasaki.

Radiation-induced skin carcinomas of the head and neck

Radiation exposures to the scalp during childhood for tinea capitis were associated with a fourfold increase in skin cancer, primarily basal cell carcinomas, and a threefold increase in benign skin tumors. Malignant melanoma, however, was not significantly elevated. Overall, 80 neoplasms were identified from an extensive search of the pathology logs of all major hospitals in Israel and computer linkage with the national cancer registry. Radiation dose to the scalp was computed for over 10,000 persons irradiated for ringworm (mean 7 Gy), and incidence rates were contrasted with those observed in 16,000 matched comparison subjects. The relative risk of radiogenic skin cancer did not differ significantly between men or women or by time since exposure; however, risk was greatest following exposures in early childhood. After adjusting for sex, ethnic origin, and attained age, the estimated excess relative risk was 0.7 per Gy and the average excess risk over the current follow-up was 0.31/10(4) PY-Gy. The risk per Gy of radiation-induced skin cancer was intermediate between the high risk found among whites and no risk found among blacks in a similar study conducted in New York City (Shore et al., Radiat. Res. 100, 192-204, 1984). This finding suggests the role that subsequent exposure to uv radiation likely plays in the expression of a potential radiation-induced skin malignancy.

Frequent chest X-ray fluoroscopy and breast cancer incidence among tuberculosis patients in Massachusetts

The incidence of breast cancer was determined in 4940 women treated for tuberculosis between 1925 and 1954 in Massachusetts. Among 2573 women examined by X-ray fluoroscopy an average of 88 times during lung collapse therapy and followed for an average of 30 years, 147 breast cancers occurred in contrast to 113.6 expected [observed/expected (O/E) = 1.29; 95% confidence interval (CI) = 1.1-1.5]. No excess of breast cancer was seen among 2367 women treated by other means: 87 observed versus 100.9 expected. Increased rates for breast cancer were not apparent until about 10 to 15 years after the initial fluoroscopy examination. Excess risk then remained high throughout all intervals of follow-up, up to 50 years after first exposure. Age at exposure strongly influenced the risk of radiation-induced breast cancer with young women being at highest risk and those over age 40 being at lowest risk [relative risk (RR) = 1.06]. Mean radiation dose to the breast was estimated to be 79 cGy, and there was strong evidence for a linear relationship between dose and breast cancer risk. Allowing for a 10-year minimum latent period, the relative risk at 1 Gy was estimated as 1.61 and the absolute excess as 10.7 per 10(4) woman-years per gray. When compared to other studies, our data suggest that the breast is one of the most sensitive tissues to the carcinogenic force of radiation, that fractionated exposures are similar to single exposures of the same total dose in their ability to induce breast cancer, that risk remains high for many years after exposure, and that young women are especially vulnerable to radiation injury.

Chronic progressive and relapsing neuromyopathy with massive dilatations of endoplasmic reticulum in muscle fibers

Large intracytoplasmic inclusions arising from the endoplasmic reticulum and nuclear envelope were found in the muscle fibers of a 32-year-old individual with a life-long, chronic and progressive sensory-motor neuropathy. The morphological features of the inclusions were similar to that occasionally reported in the striated muscles in several unrelated conditions as well as to "hyaline" or "colloid" inclusions commonly seen in motor neurons of the brain stem and spinal cord. The chemical nature of the inclusions is not known. Their occurrence in the muscle fibers is probably secondary to chronic denervation.

Weight-training injuries in adolescents

We studied the incidence of injury caused by weight training in junior and senior high school football players. Three hundred fifty-four subjects completed a retrospective injury questionnaire; histories were confirmed for high school athletes. Cumulative incidence and incidence rates were determined for injuries causing more than 7 days of missed participation. The cumulative incidences of injuries were as follows: all athletes, 7.6% (27/354); junior high school athletes, 7.1% (7/98); high school freshman/junior varsity athletes, 9.4% (15/159); and high school varsity athletes, 5.2% (5/97). The total incidence rate was 0.082 injuries per person-year, with 0.11 injuries per person-year in junior high school athletes, 0.091 injuries per person-year in high school freshman/junior varsity players, and 0.051 injuries per person-year in high school varsity players. Differences in the incidence measures among groups were not statistically significant. The most common injury type was a strain (74.1%), and the most common site was the back (59.3%). Certain exercise apparently caused more back injuries in older athletes.

Long-term serum creatinine values after radical nephrectomy

Both pre- and postnephrectomy levels of serum creatinine were measured in 52 consecutive patients who underwent radical nephrectomy for localized renal cell carcinoma between 1971 and 1976. At the time of follow-up, 17 patients were alive and 35 had died, 14 of renal cell carcinoma and 21 of other causes. Follow-up lasted a minimum of 115.5 months (mean 151.1 months, median 141.1, range 115.5-211.3 months) for 16 of the 17 patients who were alive. In this group only 2 patients had elevations in the serum creatinine level above 1.6 mg/dL-1.9 mg/dL and 2.4 mg/dL, respectively. The patient whose value was 2.4 mg/dL was a diabetic who required insulin. No serious renal failure, renal disease, or tumors in the contralateral kidney occurred among the total group of 52 patients. These data indicate that renal function remains adequate in patients who have a normal contralateral kidney and are treated by radical nephrectomy.

Indicators of mental hospital bed use

This study explored the use of survivorship curves as a type of indicator of lengths of hospital stay. Using data from the psychiatric services of a single Region, an attempt was made to determine the existence of a performance indicator with the advantages of fixed cohort analysis. By comparison with the proposed Department of Health indicators, this approach offers advantages in that it is less distorted by the presence in a District of large numbers of long-stay beds. However, although the findings show that patients are discharged more slowly from Districts with a large mental hospital and that a greater proportion of patients are still resident one year after admission, it is important to stress that measures of bed use of this type alone are not an indication of the quality of psychiatric services provided.

Thyroid neoplasia following low-dose radiation in childhood

The thyroid gland is highly sensitive to the carcinogenic effects of ionizing radiation. Previously, we reported a significant increase of thyroid cancer and adenomas among 10,834 persons in Israel who received radiotherapy to the scalp for ringworm. These findings have now been extended with further follow-up and revised dosimetry. Overall, 98 thyroid tumors were identified among the exposed and 57 among 10,834 nonexposed matched population and 5392 sibling comparison subjects. An estimated thyroid dose of 9 cGy was linked to a fourfold (95% Cl = 2.3-7.9) increase of malignant tumors and a twofold (95% Cl = 1.3-3.0) increase of benign tumors. The dose-response relationship was consistent with linearity. Age was an important modifier of risk with those exposed under 5 years being significantly more prone to develop thyroid tumors than older children. The pattern of radiation risk over time could be described on the basis of a constant multiplication of the background rate, and an absolute risk model was not compatible with the observed data. Overall, the excess relative risk per cGy for thyroid cancer development after childhood exposure is estimated as 0.3, and the absolute excess risk as 13 per 10(6) PY-cGy. For benign tumors the estimated excess relative risk was 0.1 per cGy and the absolute risk was 15 per 10(6) PY-cGy.

Disease prevention models of voluntary confidential screening for human immunodeficiency virus (HIV)

Epidemic models are developed to evaluate the potential benefits of voluntary confidential testing (VCT) for HIV. The number of tests required to prevent one case (called the economic ratio ER), and the number of cases prevented by the screening programme are calculated. Methods differ from commonly used epidemic models because susceptibles and infecteds are subdivided according to testing status, to permit modelling of the efficacy of knowledge of HIV status in retarding epidemic spread. The methods also allow for subdivision into several homogeneous subpopulations whose members may be attracted in varying degrees to members of other subpopulations. Thus the common assumption of free mixing across subpopulations is relaxed. The following conclusions which refer to a population of 100,000 persons over a period of 5 to 15 years, are robust to wide variations in assumed parameter values and other aspects of modelling: 1. VCT prevents hundreds or thousands of infections in isolated high risk populations and ER values are typically less than 100 making VCT very attractive economically. 2. VCT prevents only a few infections in isolated low risk populations with initial prevalence 0.1 per cent or less, and the ER values are well above 2000. However, in 'low risk' populations with 1 per cent initial prevalence, tens or hundreds of infections may be prevented, and ER values fall below 2000 for plausible spread rates, indicating that VCT may be economically feasible in such settings. 3. In a mixed population of gays, bisexuals and heterosexuals, a VCT programme that aims primarily at the gay/bisexual subpopulations prevents more disease in the gay/bisexual populations, prevents more disease in the heterosexual populations, and requires fewer tests per case prevented than a VCT programme that tests all subpopulations equally.