Immunization with soluble BDC 2.5 T cell receptor-immunoglobulin chimeric protein:antibody specificity and protection of nonobese diabetic mice against adoptive transfer of diabetes by maternal immunization

The BDC 2.5 T cell clone is specific for pancreatic beta-cell antigen presented by I-Ag7, and greatly accelerates diabetes when injected into 10-21-d-old nonobese diabetic (NOD) mice. The BDC 2.5 T cell receptor (TCR) has been solubilized as a TCR-IgG1 chimeric protein. All NOD mice immunized against BDC 2.5 TCR-IgG1 produced antibodies recognizing TCR C alpha/C beta epitopes that were inaccessible on the T cell surface. 56% of the mice produced antibodies against the BDC 2.5 clonotype that specifically blocked antigen activation of BDC 2.5 cells. We have used the adoptive transfer model of diabetes to demonstrate that maternal immunization with soluble TCR protects young mice from diabetes induced by the BDC 2.5 T cell clone.

Radiobiologically based assessments of the net costs of fractionated radiotherapy

PURPOSE

To examine how the long-term costs of radiation therapy may be influenced by modifications to fractionation schemes, and how any improvements in tumor control might, in principle, be translated into a potential cost saving for the responsible healthcare organization.

METHODS AND MATERIALS

Standard radiobiological modeling based on the linear-quadratic (LQ) model is combined with financial parameters relating to the estimated costs of different aspects of radiotherapy treatment delivery. The cost model includes provision for the long-term costs of treatment failure and enables the extra costs of near optimal radiotherapy to be balanced against suboptimal alternatives, which are more likely to be associated with further radiotherapy, salvage surgery, and continuing care.

RESULTS

A number of caveats are essential in presenting a model such as this for the first time, and these are clearly stated. However, a recurring observation is that, in terms of the whole cost of supporting a patient from first radiotherapy treatment onwards, high quality radiotherapy (i.e., based on individual patterns of fractionation that are near optimal for particular subpopulations of tumor) will frequently be associated with the lowest global cost.

CONCLUSIONS

This work adds weight to the case for identifying fast and accurate predictive assay techniques, and supports the argument that suboptimal radiotherapy is usually more costly in the long term. Although the article looks only at the cost-benefit consequences of altered patterns of fractionation, the method will, in principle, have application to other changes in the way radiotherapy can be performed, e.g., to examining the cost-benefit aspects of tumor dose escalation as a consequence of using advanced conformal treatment planning (10).

Bladder dose estimation during intracavitary brachytherapy for carcinoma of the cervix using a single line source system

The estimation of maximum bladder doses from orthogonal radiographs is unreliable when triple source systems are used for intracavitary brachytherapy (BT) for gynaecological cancers. For single line source systems, the estimation of maximum bladder doses from radiographs should be more reliable due to the radial symmetry of the isodose distribution. A pilot study has been carried out to compare the estimated maximum bladder doses from standard radiographs with data obtained from CT for single line source BT treatments. 12 patients undergoing treatment for carcinoma of the cervix were selected for CT assessment of their bladder doses. For each patient, the dose rates at the International Commission of Radiation Units and Measurements (ICRU) bladder reference point B1 and a second reference point B2 2.5 cm cranially were computed from orthogonal radiographs and were compared with the maximum bladder dose rate as determined by CT scanning. Dose rates were computed for two different source loading patterns: (1) a 6 cm line source with uniformly distributed linear activity along its length; (2) a 6 cm line source with increased activity in the central 2 cm segment. The mean ratio of the maximum CT bladder dose rate to the dose rate at the ICRU reference point B1 on orthogonal radiographs for the line source with uniform linear activity was 1.32 (range 0.62-2.43, SD = 0.54). When the dose rates at both reference points B1 and B2 were considered, the mean ratio of the maximum CT dose rate to the maximum dose rate from radiographs was only 1.05 (range 0.72-1.72, SD = 0.24). For the line source with increased activity in the central segment, the mean ratio of the maximum CT bladder dose rate to the dose rate at B1 was 1.38 (range 0.60-2.63, SD = 0.64). When both B1 and B2 were considered, the variation in the ratio of the maximum CT dose rate to the maximum dose rate from radiographs was considerably smaller (mean ratio = 1.07, range 0.69-1.76, SD = 0.26). For single line source systems, single point dose estimation using the ICRU reference point on orthogonal radiographs will underestimate the maximum bladder dose although the discrepancy is less than for triple source systems. If the ICRU reference point is used in conjunction with a second reference point 2.5 cm cranially, then underestimation of the maximum bladder dose is unlikely to occur as at least one of the points is likely to be a reasonable estimate of the maximum bladder dose.

Hyaluronan turnover in the synovial fluid in metacarpophalangeal--and middle carpal joints in standardbred horses

The biological turnover of hyaluronan (sodium hyaluronate) of different molecular weights (0.6 x 10(6) and 2.5 x 10(6) Daltons) was studied in the synovial fluid of the middle carpal and metacarpophalangeal joints of 6 clinically healthy Standardbred horses. The hyaluronan was radioactively labelled with 14C. The biological half-life (t1/2) was calculated from repeated synovial samples after injection of the labelled hyaluronan. The mean t1/2 in the metacarpophalangeal joints was 9.7 h for low molecular weight hyaluronan and 8.9 h for high molecular weight hyaluronan and in the middle carpal joints 16.0 h and 12.5 h respectively. These was no significant difference in turnover of the different molecular weights of hyaluronan.

The reduction of tumour control with increasing overall time: mathematical considerations

The rate of loss of tumour control (dP/dt) with extension of treatment time is analysed to assess the relative contributions of radiobiological parameters (radiosensitivity, clonogen doubling time, clonogen numbers and fractionation schedule) on such loss. Linear quadratic modelling and Poisson statistics are used to study individual tumour responses. A heterogeneous tumour population is constructed by the use of random sampling techniques to allow for variations in intrinsic radiosensitivity and clonogen doubling times. Average tumour control probability is calculated for this population for two different fractionation schedules (60 Gy in 30 fractions and 50 Gy in 15 fractions), each given over 15-60 days. The magnitude of dP/dt will depend upon the tumour cure probability (P): the loss of control will be most significant for tumours which have a cure of 37% when the Poisson survival model is used. The analysis suggests that compensation for short unscheduled treatment gaps (e.g. by increasing the total dose or rescheduling with use of weekend treatment sessions) may only be required for difficult tumours (i.e. radioresistant and/or with short clonogen doubling times). Where pre-treatment clonogen numbers are relatively low as in small volume tumours or after surgical debulking, the model predicts that correction for short treatment gaps is probably not required if the average effective clonogen doubling times are longer than 5 days. Different dose-time-fractionation schedules, even though producing similar overall cure rates in clinical practice, may actually be achieving cures in different subpopulations within a population of tumours, since the value of dP/dt in each individual tumour will depend upon the set of radiobiological parameters given above. For a hypothetical randomly selected heterogeneous tumour population the predicted rates of loss of tumour control produced by an extension in treatment time are 0.9 and 1.1% per day, respectively, for the above fractionation schedules. These values are close to those reported in the clinical literature for the first 2 weeks of treatment prolongation (1-2% per day for squamous cell carcinomas). The Poisson method, when combined with random sampling techniques, consequently provides realistic data. Modelling of this clinical problem provides an insight into how tumour sub-populations, each characterized by its own set of radiobiological parameters, can influence the overall rate of loss of tumour control in a heterogeneous population. Random sampling techniques should be considered as necessary precursors for the assessment of the choices of dose-fractionation in future clinical trials particularly when more precise data regarding the radiobiological parameters and their statistical variations become available.

Difference between delivered and prescribed blood flow in hemodialysis

The authors compared delivered and prescribed blood flow (QB) during 208 hemodialysis treatments using the Transonic hemodialysis monitor (Transonic Systems, Inc, Ithaca, New York). Delivered QB averaged 205.6, 300.6, 384.3 (p < .0001), and 467.7 cc/min (p < .0001) at pump settings of 200, 300, 400, and 500 cc/min. Permcaths had significantly lower delivered QB (188, 266, and 314 cc/min at 200, 300, and 400 pump settings) (p < .01). When catheters were excluded, delivered QB was at least 10% less than prescribed in 13.5%, 18.4%, and 20.8% of patients (300, 400, and 500 pump settings). Patients using 14 gauge arterial needles had higher delivered QB than patients using 15 gauge needles (418 vs 383 cc/min at 400 pump; p < .0001). Patients on Baxter 550 machines had lower delivered QB (294 and 376 ml/min) than those on fresenius 2008H machines (323 and 411 ml/min) at 300 and 400 pump settings, respectively (p < .0001). Excluding catheters, 17.4% and 23.4% of patients on Baxter machines had delivered QB of 10% less than prescribed, compared to 2.1% and 4.3% of patients on Fresenius machines at 300 and 400 pump settings. In conclusion, delivered QB during hemodialysis is often significantly less than prescribed QB. Further studies are necessary to determine the factors involved in these differences.

The influence of air cavities on the optic chiasm dose during pituitary radiotherapy for acromegaly

The treatment planning of acromegalic patients can be complicated by the presence of abnormally large frontal air sinuses which allow increased anterior beam transmission causing increased dose to the optic nerve and chiasm which, if excessive, can result in blindness. This potential problem has been investigated by computer treatment planning exercises which have allowed for a variable thickness (1-3 cm) of air cavity beneath the frontal field and for different weightings of the lateral opposed fields relative to the anterior field. The resultant overdosage can be greater than 5% of the intended dose. The increased biological effect from errors of this magnitude is sufficient to increase the risk of optic nerve damage since neural tissue is very sensitive to small increments in fraction size. Even when the reduced attenuation is allowed for in the computer plan, the thickness of the air sinuses varies across the field so that irradiation through the frontal enlarged frontal air sinuses causes inhomogeneous dose distributions in the target volume. Acromegalic patients should therefore be treated with a more superior beam which would avoid the air sinuses altogether.

A clinical and academic outcome study of children attending a day treatment program

OBJECTIVE

To assess the behavioural and academic improvement of children who attended a day treatment program during a defined period of time.

METHOD

Forty-six children admitted consecutively to the project were assessed on admission and discharge using behavioural and academic measures. They also had intelligence and language assessments. The subjects attended the program for one academic year, on the average. The large majority presented with disruptive behaviour disorders and low academic achievement levels.

RESULTS

There was a significant improvement reported by the parents in externalizing (P < 0.001) and internalizing (P < 0.05) behaviour. The subjects also gained one academic year, but their levels continued to be low in terms of percentiles. Measures of academic improvement showed significant associations with cognitive measures only (subscales of Wechsler Intelligence Scale for Children-Revised [WISC-R] and Clinical Evaluation of Language Fundamentals-Revised [CELF-R]).

CONCLUSION

A day treatment and school program is an effective modality for treatment and remediation of children with severe psychiatric disorders. The academic underachievement may be resistant to remediation within the limited period of attendance in such a program.

Helping health professionals involved in cancer care acquire key interviewing skills--the impact of workshops

To assess the impact of workshops on key interviewing skills, 169 health professionals involved in cancer care interviewed a simulated patient immediately before and after the workshops and 6 months later. Each interview was audiotaped, transcribed and rated by trained raters using a newly developed rating system which permits an utterance by utterance analysis. The workshops led to significant increases in the use of three behaviours which promote patient disclosure of key concerns. Namely, open directive questions, questions with a psychological focus and clarification of psychological aspects. However, there was no increase in the use of educated guesses and empathic statements which promote disclosure of key problems and feelings. There were significant reductions in behaviours which inhibit disclosure including the use of questions with a physical focus, utterances clarifying physical aspects and the giving of advice prematurely. These significant gains were still evident 6 months later, but there had been some decline over time. There were also significant improvements in the ability of health professionals to elicit patients key problems. Before the workshop, 75 (44%) participants were able to identify at least 60% of their patients' main problems (a criterion of clinical competence) compared with 119 (70%) at 6-month follow-up, an increase in numbers of 59%. Before training, health professionals used as many behaviours which inhibit disclosure as those that promote it. This was unaffected by their professional discipline, prior training or age. It highlights the need for health professionals involved in cancer care to have training in these communication skills. We believe that more intensive group work in smaller groups which focuses on the feelings and attitudes of participants as well as their interviewing behaviour would lead to an increase in the use of educated guesses and empathy and better exploration of patients' feelings.

Modelling and design of cross-over trials

There are many diseases and conditions that can be studied using a cross-over clinical trial, where the subjects receive sequences of treatments. The treatments are then compared using the repeated measurements taken 'within' subjects. The actual plan or design of the trial is usually obtained by consulting a published table of designs or by applying relatively simple rules such as using all possible permutations of the treatments. However, there is a danger is this approach because the model assumed for the data when the tables or rules were constructed may not be appropriate for the new trial being planned. Also, there may be restrictions in the new trial on the number of treatment sequences that can be used or on the number of periods of treatment particular subjects can be given. Such restrictions may mean that a published design of the ideal size cannot be found unless compromises are made. A better approach is to make the design satisfy the objectives of the trial rather than vice versa. In this paper we describe an approach to constructing such tailor-made designs which we hope will lead to ill-fitting 'off the peg' designs being a thing of the past. We use a computer algorithm to search for optimal designs and illustrate it using a number of examples. The criterion of optimality used in this paper is A-optimality but our approach is not restricted to one particular criterion. The model used in the search for the optimal design is chosen to suit the nature of the trial at hand and as an example a variety of models for three treatments are considered. We also illustrate the construction of designs for the comparison of two active treatments and a placebo where it can be assumed that the carry-over effects of the active treatments are similar. Finally, we illustrate an augmentation of a design that could arise when the objectives of a trial change.

Trials to assess equivalence: the importance of rigorous methods

The aim of an equivalence trial is to show the therapeutic equivalence of two treatments, usually a new drug under development and an existing drug for the same disease used as a standard active comparator. Unfortunately the principles that govern the design, conduct, and analysis of equivalence trials are not as well understood as they should be. Consequently such trials often include too few patients or have intrinsic design biases which tend towards the conclusion of no difference. In addition the application of hypothesis testing in analysing and interpreting data from such trials sometimes compounds the drawing of inappropriate conclusions, and the inclusion and exclusion of patients from analysis may be poorly managed. The design of equivalence trials should mirror that of earlier successful trials of the active comparator as closely as possible. Patient losses and other deviations from the protocol should be minimised; analysis strategies to deal with unavoidable problems should not centre on an "intention to treat" analysis but should seek to show the similarity of results from a range of approaches. Analysis should be based on confidence intervals, and this also carries implications for the estimation of the required numbers of patients at the design stage.

Regional hypothermia in response to minor injury

Minor injuries are sometimes followed by a potentially disabling syndrome of hyperalgesia, hyperesthesia, allodynia, and sudomotor disturbance as well as, eventually, weakness, muscle atrophy, trophic skin changes, and bone and joint abnormalities. Vasomotor changes frequently present as hypothermia or hyperthermia. Most of the literature refers to this syndrome as reflex sympathetic dystrophy (RSD). To observe possible early RSD changes, we studied 1000 military recruits before and during basic training. Evaluations consisted of lower limb clinical examinations and pain assessment. Infrared images were taken of anterior, posterior, medial, lateral legs, and plantar surface of the feet. If the clinical examination suggested a possible stress fracture, a bone scan was performed. Recruits were studied before training and again each time musculoskeletal complaints arose. The controls were recruits tested before the onset of training who had no musculoskeletal complaints. Two-hundred seven soldiers were injured. Regional hypothermia was noted in 8.6% of all thermograms, with 75% on the left and 25% on the right. The most common injuries causing this phenomenon were ankle pain/sprain and minor foot stress fractures, especially the left metatarsals. Hypothermia occurred within 24 to 48 h, usually beginning in the periphery and ascending proximally, lasting a few days to 6 wk (end of study). None of the recruits developed the full syndrome of RSD during the study period. Whether the continued training, even though modified, helped to prevent this complication or the observed post-traumatic hypothermia has no relationship to RSD needs to be determined.

Maladaptive coping and affective disorders among cancer patients

Coping has attracted much attention in research as a possible mediator of the psychological impact of cancer. Yet, conceptual ambiguity and methodological limitations have resulted in weak and contradictory findings. A major shortcoming has been the use of designs which do not represent adequately the complexity or the diversity of demands which arise from the diagnosis and treatment of cancer. The neglect of appraisal in the assessment of the relationship between coping and mental health is of particular concern, given the role it has been found to play in the onset and maintenance of affective disorders. In a prospective study 673 newly diagnosed cancer patients were interviewed 4 to 8 weeks and 1 year later to assess the effects of their appraisals, coping responses and resolution of any concerns on subsequent mental health. Logistic regression analyses, adjusted for possible confounding variables, were used to investigate the relationships between coping variables and affective disorders. When examined separately the degree of threat appraised, the reporting of a helpless response and perceived success of primary responses in resolving concerns all predicted subsequent effective disorder. However, in a multivariate model only appraisal and success of the response in resolving the concern were significant. No response was found to prevent affective disorders, however certain types of responses were associated with the resolution of specific concerns. The results highlight the importance of assessing the whole coping process and the need to address the complex and multifaceted characteristics of cancer demands. On the basis of our findings we describe a maladaptive cycle of coping, which we believe contributes to the later onset of affective disorders in cancer patients.

Age of onset in familial and sporadic schizophrenia

We have studied the gender and family history differences with regard to age of onset of schizophrenia. These differences have often been viewed as an important clue to the aetiology of the illness. Patients from three centres in Europe and Canada were included in the study. A sample of 1089 subjects was categorized according to the subject's sex, family history of schizophrenia, and the centre. The principal statistical method was analysis of variance. Patients with no family history of schizophrenia had a consistently higher average age of onset. This effect was seen in both male and female subjects across all three groups. These results support the relationship between familial risk and early onset, but no interaction of gender and family history was found.

Reading and spelling deficits among children attending a psychiatric day treatment program

To investigate the specific behavioural and cognitive characteristics which may account for academic deficits in children with psychiatric disorders, 50 children admitted to a day treatment and school program were assessed using behaviour questionnaires for parents and teachers, and tests assessing intelligence (WISC-R), language (CELF-R) and academic performance (Kaufman Test of Educational Achievement). The academic measures Reading Decoding, Reading Comprehension and Spelling formed the dependent variables. Behaviour and cognitive measures which distinguished the sample from normative data constituted the independent variables. Hierarchical multiple regression analyses were performed in order to identify behaviour and cognitive measures accounting for the academic deficits. In the analyses, three measures (Digit Span, Sentence Assembly, Recalling Sentences), probably assessing overlapping cognitive/linguistic functions, accounted for a large proportion of variance for Reading Decoding (0.47), Reading Comprehension (0.63) and Spelling (0.29). None of the behaviour measures accounted for any variance of the academic variables. It is argued that linguistic dysfunction is a primary deficit which underlies problems in academic learning.

Systemic anomalies in 77 patients with congenital anophthalmos or microphthalmos

Congenital anophthalmos and microphthalmos are rare conditions which can have associated pathology in the second eye and/or systemic anomalies. A retrospective review of 77 patients with congenital anophthalmos or microphthalmos seen at Moorfields Eye Hospital over a 13 year period was performed. A detailed description of the ocular and systemic anomalies present in our series of patients is given, and the current understanding of the pathogenesis of congenital anophthalmos and microphthalmos is reviewed.

Analysis of cross-over trials for duration data

Survival models and cross-over designs both have an established place in biomedical research. Surprisingly, there are a few examples of proper exploitation of two in combination. A number of advantages and disadvantages of such studies are discussed. Two examples are used to illustrate the application of semi-Markov models with time-varying covariates, as standard log-linear models, to such data.

Abnormal saccadic distractibility in patients with schizophrenia: a 99mTc-HMPAO SPET study

Recent research has shown that some patients with schizophrenia have a severe impairment in the suppression of reflexive saccadic eye movements in the ANTI-saccade task. This saccadic distractibility has previously been found in patients with lesions of dorsolateral prefrontal cortex, implicating an abnormality of prefrontal cortex. The objective of the present study was to determine the contribution of these and other areas to the ANTI-saccadic abnormality in schizophrenia by functional neuroimaging. Using 99mtechnetium-HMPAO high resolution multidetector single-photon emission tomography, regional cerebral blood flow (rCBF) during performance of the ANTI-saccade eye-movement task was compared, by statistical parametric mapping, in ten male schizophrenic patients on stable antipsychotic medication who had a high distractibility error rate on the task, and eight similar patients who had normal distractibility error rates. Compared with the normal error group, the patients with high error rates showed significantly decreased rCBF bilaterally, in the anterior cingulate, insula, and in left striatum. These same patients also had increased perseverative errors on the Wisconsin Card Sort Test.

Establishing a reliable visual function test and applying it to screening optic nerve disease in onchocercal communities

The computer Controlled Video Perimetry (CCVP) is a computer screening test for detecting visual function loss caused by onchocerciasis, glaucoma, etc. Installed on portable computers, the CCVP has been shown to be high acceptability in field community investigation. However, it is regarded to be difficult in obtaining reliable results from portable computer screening tests because of human behavioural variants and the lack of standard testing environment. In this paper, we propose an architecture for implementing a more reliable CCVP system. In particular, a self-organising neural network is applied to manage measurement noise caused by behavioural factors. A control unit is introduced to manage the overall behaviour of the system. The integrated test system has been used to screen optic nerve disease in onchocercal communities of rural Nigeria and the experimental results obtained from a large number of test records are very encouraging: reliable results from volatile test environments may be obtained using the proposed method.

A model for cross-over trials evaluating therapeutic preferences

A preference trial is a special form of cross-over trial where clinical conditions determine when patients change treatment, in a prescribed order. This can be modelled using a geometric distribution. The model can be simply fitted using standard logistic regression methodology. The procedure is applied to a trial studying the effects of bronchodilators in the treatment of chronic asthma.