Evaluation of dose-response models and parameters predicting radiation induced pneumonitis using clinical data from breast cancer radiotherapy

The purpose of this work is to evaluate the predictive strength of the relative seriality, parallel and LKB normal tissue complication probability (NTCP) models regarding the incidence of radiation pneumonitis, in a large group of patients following breast cancer radiotherapy, and furthermore, to illustrate statistical methods for examining whether certain published radiobiological parameters are compatible with a clinical treatment methodology and patient group characteristics. The study is based on 150 consecutive patients who received radiation therapy for breast cancer. For each patient, the 3D dose distribution delivered to lung and the clinical treatment outcome were available. Clinical symptoms and radiological findings, along with a patient questionnaire, were used to assess the manifestation of radiation-induced complications. Using this material, different methods of estimating the likelihood of radiation effects were evaluated. This was attempted by analysing patient data based on their full dose distributions and associating the calculated complication rates with the clinical follow-up records. Additionally, the need for an update of the criteria that are being used in the current clinical practice was also examined. The patient material was selected without any conscious bias regarding the radiotherapy treatment technique used. The treatment data of each patient were applied to the relative seriality, LKB and parallel NTCP models, using published parameter sets. Of the 150 patients, 15 experienced radiation-induced pneumonitis (grade 2) according to the radiation pneumonitis scoring criteria used. Of the NTCP models examined, the relative seriality model was able to predict the incidence of radiation pneumonitis with acceptable accuracy, although radiation pneumonitis was developed by only a few patients. In the case of modern breast radiotherapy, radiobiological modelling appears to be very sensitive to model and parameter selection giving clinically acceptable results in certain cases selectively (relative seriality model with Seppenwoolde et al and Gagliardi et al parameter sets). The use of published parameters should be considered as safe only after their examination using local clinical data. The variation of inter-patient radiosensitivity seems to play a significant role in the prediction of such low incidence rate complications. Scoring grades were combined to give stronger evidence of radiation pneumonitis since their differences could not be strictly associated with dose. This obviously reveals a weakness of the scoring related to this endpoint, and implies that the probability of radiation pneumonitis induction may be too low to be statistically analysed with high accuracy, at least with the latest advances of dose delivery in breast radiotherapy.     

Transmitter characteristics of small mesenteric arteries from the rat

We have studied the neurogenic response of small mesenteric arteries from the rat to evaluate the involvement of possible co-transmitters under various modes of stimulation. Segments of small branches of the mesenteric artery were mounted in a myograph and the intramural nerves were activated with transmural electrical stimulation. A single stimulation of the nerves caused a contraction that was reduced by only 20% in the presence of adrenergic blocking agents (prazosin or phenoxybenzamine), whereas the steady-state response to continuous nerve stimulation of high frequency was reduced by 90-95%. In contrast, all responses to applied noradrenaline in doses up to at least 1 mM were eliminated by phenoxybenzamine treatment. The stable ATP analogue, alpha,beta-methylene ATP, reduced the response to a single nerve stimulation by 70%, but reduced the contraction caused by continuous high-frequency nerve stimulation by only 10%. None of these agents affected the response to applied neuropeptide Y (NPY). The response of relaxed vessels to nerve stimulation was totally blocked by the combination of an adrenoceptor-blocking agent and alpha,beta-methylene ATP, although even in this situation a further neurogenic response could be revealed in vessels precontracted with vasopressin. Responses to either single stimuli or brief burst stimulations were potentiated after high-frequency stimulation. Both the adrenergic and non-adrenergic components were enhanced to roughly the same extent. Also the potentiated response was eliminated by the combined application of prazosin and alpha,beta-methylene ATP. The non-adrenergic transmitter in the sympathetic nerves of small arteries thus appears to be the dominant transmitter during low-frequency nerve stimulation, causing rapid but phasic activation. Noradrenaline is the most important transmitter for higher frequencies, exerting slower but sustained contractions. The post-stimulatory potentiation affects both the adrenergic and the non-adrenergic part of the neurogenic response.     

Modulation of IgG effector functions by a monovalent fragment of staphylococcal protein A

The monovalent V-1 fragment of protein A (fSpA) with a mol. wt of 13,000 obtained from an u.v. mutant of Staphylococcus aureus Cowan I strain was proved to be able to modulate significantly some of the effector functions of IgG, such as complement fixation, catabolism, attachment to Fc receptors and antibody-dependent cell-mediated cytotoxicity. Moreover fSpA-like protein A obtained from the A676 strain is mitogenic and enhances NK activity of human peripheral lymphocytes. The efficiency of fSpA was found to be lower than that of protein A with regard to its ability to inhibit complement fixation, EA rosette formation and antibody-dependent cell-mediated cytotoxicity. Both protein A and fSpA had the same efficiency in activation of the complement system after reaction with human or guinea pig IgG, and in increasing the IgG catabolism. Unlike fSpA the monovalent B fragment of protein A (with mol. wt of 7000) was not able to inhibit EA rosette formation and antibody-dependent cell-mediated cytotoxicity. The results recommend fSpA, substituting for protein A, as a molecular probe for the investigation of IgG antibody and lymphocyte effector functions.     

Tacrine restores cholinergic nicotinic receptors and glucose metabolism in alzheimer patients as visualized by positron emission tomography

Three patients with Alzheimer's disease, a 68-year-old woman with mild dementia and 2 men (aged 64 and 72 years) with moderate dementia were treated orally with the cholinesterase inhibitor tacrine (tetrahydroaminoacridine), 80 mg daily, for several months. The patients were investigated using positron emission tomography (PET) prior to, and after 3 weeks and 3 months of treatment. The PET studies involved a multi-tracer system consisting of [¹⁸F]-fluoro-deoxy-glucose (¹⁸F-FDG) (tracer for glucose metabolism); ¹¹C-butanol (cerebral blood flow) and (S)(−)- and (R)(+)-[N-¹¹C-methyl]-nicotine (nicotinic receptors; cholinergic neural activity). Tacrine treatment increased the uptake of ¹¹C-nicotine to the brain. Significant reduced difference in uptake between the two enantiomers (S)(−)- and (R)(+)¹¹C-nicotine was observed in the frontal and temporal cortices after tacrine treatment in all three patients. The kinetic analysis indicated increased binding of (S)(−)¹¹C-nicotine in brain compatible with a restoration of nicotinic cholinergic receptors. The most pronounced effect was observed after 3 weeks and 3 months treatment in the patient with mild dementia. An increase in cerebral glucose utilization was found in the 68-year-old patient with mild dementia but also slightly in the 64-year-old man with moderate dementia when treated with tacrine for 3 months. Tacrine administration did not affect cerebral blood flow. The PET data obtained after 3 weeks of tacrine treatment was paralleled by improvement in neuropsychological performance. This study shows in vivo by PET neurochemical effects induced in brain by treatment with tacrine to Alzheimer patients. Intervention with tacrine in the early course of the disease might be necessary for clinical improvement.     

An ELISA for the detection of anti-neutrophil cytoplasm antibodies (ANCA)

An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of circulating anti-neutrophil cytoplasm antibodies (ANCA), which are defined by a diffuse, granular staining of the cytoplasm of alcohol-fixed human neutrophils by indirect immunofluorescence (IIF). Detection of antineutrophil cytoplasm antibodies has a high sensitivity and specificity for active Wegener's granulomatosis (WG) and reflects the effect of treatment. In the present enzyme-linked assay, immunoplates were coated with the cytoplasmic alpha fraction of neutrophils obtained from apparently healthy human donors by nitrogen bomb cavitation and subsequent Percoll gradient centrifugation. Alkaline phosphatase-labelled anti-human IgG was used as a secondary antibody. Diluted sera from 70 patients with WG and 16 patients with other diseases with anti-myeloperoxidase antibodies (anti-MPO) were examined. It is concluded that the ELISA accurately detects IIF ANCA positive patients with WG, is helpful in detecting WG patients in remission, is not influenced by the presence of anti-MPO and may help in detecting ANCA in cases with granulocyte-specific anti-nuclear antibodies since this IIF pattern obscures the IIF ANCA patterns. The ELISA with titration can be carried out in 3.5 h whereas a rapid test just to detect ANCA can be performed in 30 min.     

Estimation of genetic risk for type 1 diabetes

The most important gene loci defining risk of type 1 diabetes mellitus (T1DM) are located within the HLA gene region. HLA-DQ molecules are of primary importance but HLA-DR gene products modify the risk conferred by HLA-DQ. The risk associated with an HLA genotype is defined by the particular combination of susceptible and protective alleles. The highest risk is associated with a combination of two different risk haplotypes (7% risk to develop T1DM in Finland) whereas protective genotypes covering 69% of population have a risk of less than 0.2%). The complicated analysis of HLA genotypes is simplified by strong linkage disequilibrium between HLA-DRB1, -DQA1 and -DQB1 loci. In many cases one can deduce the alleles of other loci based on determination of the alleles in one locus. Differences between various populations in the frequency of marker alleles and in the linkages between them has to be taken into account. We have developed PCR based typing methods that utilize blood spot samples, microtiter plate format and lanthanide labeled oligonucleotide probes to define HLA-DQ and -DR alleles relevant for T1DM risk. Typing is run stepwise so that after initial HLA-DQB1 typing only those samples will be further analyzed in which -DQA1 or -DRB1 typing is informative and expected to contribute to the risk estimation. This method has been used to screen more than 50,000 newborn infants in Finland over a time period of 6 years, and it has been able to identify most children who have developed T1D during the follow-up period. The efficiency of the procedure has also been tested in Finnish and Greek populations.