Short-term outcome of psychogenic non-epileptic seizures after communication of the diagnosis

We previously described a communication strategy for the delivery of the diagnosis of psychogenic non-epileptic seizures (PNES) that was acceptable and effective at communicating the psychological cause of PNES. This prospective multicenter study describes the short-term seizure and psychosocial outcomes after the communication of the diagnosis and with no additional treatment. Participants completed self-report measures at baseline, two and six months after the diagnosis (seizure frequency, HRQoL, health care utilization, activity levels, symptom attributions and levels of functioning). Thirty-six participants completed the self-report questionnaires. A further eight provided seizure frequency data. After six months, the median seizure frequency had dropped from 10 to 7.5 per month (p=0.9), 7/44 participants (16%) were seizure-free, and an additional 10/44 (23%) showed greater than 50% improvement in seizure frequency. Baseline questionnaire measures demonstrated high levels of impairment, which had not improved at follow-up. The lack of change in self-report measures illustrates the need for further interventions in this patient group.

Service development for intellectual disability mental health: a human rights approach

BACKGROUND

People with intellectual disability (ID) experience higher rates of major mental disorders than their non-ID peers, but in many countries have difficulty accessing appropriate mental health services. The aim of this paper is to review the current state of mental health services for people with ID using Australia as a case example, and critically appraise whether such services currently meet the standards set by the Convention on the Rights of Persons with Disabilities.

METHODS

The literature regarding the current state of mental health services for people with ID was reviewed, with a particular focus on Australia.

RESULTS

The review highlighted a number of issues to be addressed to meet the mental health needs of people with ID to ensure that their human rights are upheld like those of all other citizens. Many of the barriers to service provision encountered in Australia are likely also to be relevant to other nations, including the culture of division between disability and mental health services, the inadequate training of both disability and mental health workers in ID mental health, and the lack of relevant epidemiological data. None of these barriers are insurmountable.

CONCLUSIONS

Recommendations are made for adopting a human rights-based approach towards the development and provision of mental health services for people with ID. These include improved policy with measurable outcomes, improved service access via clear referral pathways and the sharing of resources across disability and mental health services, and improved service delivery through training and education initiatives for both the mental health and disability workforce.

A comparison of medical physics training and education programs--Canada and Australia

An overview and comparison of medical physics clinical training, academic education, and national certification/accreditation of individual professionals in Canada and Australia is presented. Topics discussed include program organization, funding, fees, administration, time requirements, content, program accreditation, and levels of certification/accreditation of individual Medical Physicists. Differences in the training, education, and certification/accreditation approaches between the two countries are highlighted. The possibility of mutual recognition of certified/accredited Medical Physicists is examined.

Defective excitation-contraction coupling in hearts of rats with congestive heart failure

AIM

We examined the cellular basis for depressed cardiac contractility in rats with congestive heart failure (CHF) secondary to myocardial infarction.

METHODS

Six weeks after ligation of the left coronary artery, CHF was confirmed by haemodynamic measures and echocardiographic demonstration of reduced myocardial contractility in vivo. Papillary muscles from CHF animals developed less force than those from sham operated (SHAM) animals. Cell shortening was measured in isolated ventricular myocytes voltage-clamped with high resistance electrodes. Ca2+ transients were measured in fluo-4 loaded myocytes.

RESULTS

Contractions triggered by depolarizing test steps from a post conditioning potential of -70 mV were significantly smaller and had significantly reduced velocity of shortening in CHF compared with SHAM myocytes. However, contractions initiated from -40 mV, were similar in amplitude and velocity of shortening in CHF and SHAM cells. L-type Ca2+ current was not significantly different between CHF and SHAM cells, whether activated from -70 or -40 mV. Therefore, in SHAM cells, excitation-contraction coupling exhibited higher gain when contractions were initiated from negative (-70 mV), as compared with depolarized potentials (-40 mV). However, in CHF myocytes, excitation-contraction coupling gain was selectively depressed with steps from -70 mV. This depression of gain in CHF was not accompanied by a significant reduction in sarcoplasmic reticulum Ca2+ content. Isoproterenol increased Ca2+ transients less in CHF than SHAM myocytes.

CONCLUSION

In this post-infarction model of CHF, the contractile deficit was voltage dependent and the gain of excitation-contraction coupling was selectively depressed for contractions initiated negative to -40 mV.

Professional holistic care of the person with a stoma: online learning

Stoma care nurse specialists are valued for their diverse expertise, but it is essential that all practitioners who regularly care for people with stomas have the opportunity to develop professionally and influence this important area of practice. The vision of a clinical and educational team from Suffolk and south Norfolk led to the development of innovative web-based learning material. The aim is to inspire nurses to engage actively with people who have a stoma. 'Professional care of the person with a stoma' is about caring for the whole person, physically and emotionally, from the period before surgery, to their continuing care in the community. An overview of four aspects of stoma care is presented here as a way of sharing with a wider audience the expert practice harnessed during the development of this web-based module.

Cluster analysis of symptoms and health seeking behaviour differentiates subgroups of patients with severe irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a heterogeneous condition which is diagnosed according to specific bowel symptom clusters. The aim of the present study was to identify subgroups of IBS subjects using measures of rectal sensitivity and psychological symptoms, in addition to bowel symptoms. Such groupings, which cross conventional diagnostic approaches, may provide greater understanding of the pathogenesis of the condition and its treatment.

METHOD

A K means cluster analysis was used to group 107 clinic patients with IBS according to physiological, physical, and psychological parameters. All patients had severe IBS and had failed to respond to usual medical treatment. Twenty nine patients had diarrhoea predominant IBS, 26 constipation predominant, and 52 had an alternating bowel habit.

RESULTS

The clusters were most clearly delineated by two variables: "rectal perceptual threshold (volume)" and "number of doctor visits". Three subgroups were formed. Group I comprised patients with low distension thresholds and high rates of psychiatric morbidity, doctor consultations, interpersonal problems, and sexual abuse. Group II also had low distension thresholds but low rates of childhood abuse and moderate levels of psychiatric disorders. Group III had high distension thresholds, constipation or alternating IBS, and low rates of medical consultations and sexual abuse.

CONCLUSION

The marked differences across the three groups suggest that each may have a different pathogenesis and respond to different treatment approaches. Inclusion of psychosocial factors in the analysis enabled more clinically meaningful groups to be identified than those traditionally determined by bowel symptoms alone or rectal threshold.

Distribution of the 3' VNTR polymorphism in the human dopamine transporter gene in world populations

A polymorphism with a variable number of tandem repeats (VNTR) found in the 3' untranslated region of the human dopamine transporter gene (DAT1) was scored in unrelated individuals drawn from 10 geographically widely dispersed populations in order to assess this marker's usefulness in human population genetics. The populations that were analyzed in this study included 4 indigenous groups of Siberia, natives of North and South America, as well as Caucasian and Oceanic groups, most of which represented small-scale societies. A total of 5 DAT1 alleles were seen overall, but only in one Siberian population, the Altai-Kizhi, were all 5 present, and in the Native Americans of Colombia the locus was monomorphic. The most common allele, DAT1*10, ranged in frequency from 52% in Greeks to 100% in South Americans. The high frequency of the DAT1*10 allele (approximately 90%) among Mongoloid groups of north and east Asia distinguishes them from most Caucasian groups. The presence of the rare DAT1*7 allele in relatively high frequency (approximately 5%) among all Siberian groups suggests a close affinity with north Asian groups, especially Mongolians. The presence of the even rarer DAT1*13 allele in one Siberian population, the Altai-Kizhi, reflects this group's long historical contact with Mongolians. The results demonstrated that the DAT1 VNTR polymorphism is useful in investigating population relationships, and that rare alleles at this locus may be particularly valuable in understanding the extent of genetic affinity between neighboring groups and in situations where admixture is suspected. However, because of both the association and linkage of this VNTR locus with attention-deficit hyperactivity disorder (ADHD) in children, and its highly restricted polymorphism (usually 3 alleles) in most human groups, the possibility of selection constraints on the DAT1 gene cannot be ignored.

Verification of the dose distribution for 192Ir mould treatments using radiochromic film and LiF:Mg,Cu,P TLDs

Radioactive moulds are an effective way of treating skin lesions. The aim of the study was to verify the dose distribution in a low dose rate 192Ir hand mould treatment using radiochromic film and LiF:Mg,Cu,P TLDs. Measurements were compared with two computerised treatment planning systems--Theraplan VO5B and ADAC Pinnacle3 V4.0b. Radiochromic film measured doses that were typically 25-30% lower than the TLD and planning computer doses (which agreed within +/- 5%). However, radiochromic film provided a two-dimensional map, which is particularly useful for dose distributions that are difficult to predict. This was demonstrated in the effects of adding thumb shielding to the hand mould. TLD results provided only point dose verification. Dose rates to the inner surface of the thumb were reduced from 15-20 cGy/hr to 2-4 cGy/hr by using 7.5 mm lead shielding. This is consistent with three half value layer reductions. For unshielded treatments, TLD results agreed with the treatment planning computers all within +/- 13%, including an uncertainty of +/- 10% on the source strength certificate for the activity. Due to the detector's sensitivity, miniaturisation would be the next approach for further more accurate verification with LiF:Mg,Cu,P TLDs.

Monitor unit calculations using a 3D computerised treatment planning system: verification in an anthropomorphic phantom

The aim of this work was to assess the monitor unit calculation accuracy of a new 3D computer planning system in a volume containing significant lung heterogeneity. An anthropomorphic phantom drilled to accommodate a cylindrical ionisation chamber was used for measurements. Results were also compared to an older 2D system and a manual calculation method. Only a slight improvement was achieved with the new system and an energy dependence was evident. This type of test is recommended before implementing a new 3D planning system.

Deletion polymorphism in the human COL1A2 gene: genetic evidence of a non-African population whose descendants spread to all continents

We report the frequencies of a deletion polymorphism at the alpha 2 (1) collagen gene (COL1A2) and argue that this distribution has major implications for understanding the evolution of modern humans immediately after their exodus from sub-Saharan Africa as well as their subsequent spread to all continents. The high frequency of the deletion in non-African populations and its complete absence in sub-Saharan African groups suggest that the deletion event occurred just before or shortly after modern humans left Africa. The deletion probably arose shortly after the African exodus in a group whose descendants were among the ancestors of all contemporary populations, except for sub-Saharan Africans. This, of course, does not imply that there was a single migration out of Africa. The GM immunoglobulin haplotype GM*A,X G displays a similar distribution to that for the COL1A2 deletion, and these 2 polymorphisms suggest that the exodus from Africa may not have been a rapid dispersion to all other regions of the world. Instead, it may have involved a period of time for the savanna-derived gene pool to adapt to novel selective agents, such as bacteria, viruses, and/or environmental xenobiotics found in both animal and plant foods in their new environment. In this context these polymorphisms are indicators of the evolution that occurred before the diaspora of these populations to the current distribution of modern peoples.

Selective in vivo dosimetry in radiotherapy using P-type semiconductor diodes: a reliable quality assurance procedure

Since 1994, our center has conducted entrance dose measurements on selected patients receiving 6MV x-ray therapy by utilizing a commercial set of p-type semiconductor diodes. We report on three years results representing 386 patients having 1005 measurements and the usefulness of such a system in a radiotherapy department. The 386 patients represent approximately 20% of our total radical treatments. Minimal disruption to patient treatment was achieved. Measurements showed an average variation from expected dose of 0.5% +/- 2.2%. Specific treatment site groups were investigated. Our results show that in vivo dosimetry on a selected group of patients is an effective method of providing an independent verification of dose delivery accuracy.

Both CD4(+) T cells and CD8(+) T cells are required for iodine accelerated thyroiditis in NOD mice

The nonobese diabetic (NOD) mouse, a spontaneous animal model for insulin-dependent diabetes mellitus, displays a tendency in common with human diabetic populations to develop autoimmune thyroiditis although incidence and severity of thyroid lesions vary widely among different colonies around the world. A congenic strain of NOD mice bearing I-Ak on a NOD background (NOD-H2(h4)) has recently been derived and displays a much greater tendency to develop thyroiditis and autoantibodies to mouse thyroglobulin (MTg) although it is free of diabetes. Both thyroid infiltrates and autoantibody formation are accelerated and enhanced in NOD-H2(h4) mice by increased iodine intake. The effect of increased iodine intake on NOD mice themselves has not been directly investigated although a recent study of these animals given high or low doses of iodine showed no follicular destruction unless the mice were first rendered goitrous by iodine deprivation. We found that dietary iodine increased both the incidence and the severity of thyroid lesions in our NOD mice although autoantibodies to MTg were absent. NOD background genes appear to be essential for the development of these lesions, which were maximal after 4 weeks of iodine administration and showed no significant regression when the iodine was stopped. Furthermore, our studies show for the first time that both CD4(+) and CD8(+) T cells are necessary for the development of this accelerated but essentially spontaneous murine thyroid disease.

Effect of the synthetic immunomodulator, linomide, on experimental models of thyroiditis

The drug Linomide is an immunomodulator showing marked down-regulation of several experimental autoimmune diseases. In this study, its effect on three different experimental models of thyroid disease and on spontaneous infiltration of salivary glands (sialoadenitis), was investigated. Although very effective at preventing thyroid infiltrates in mice immunized with mouse thyroglobulin and complete Freund's adjuvant and in spontaneous models of thyroiditis and sialoadenitis, it completely failed to modify experimental autoimmune thyroiditis (EAT) induced in mice immunized with mouse thyroglobulin and lipopolysaccharide. There was no significant shift in the observed isotypes of anti-mouse thyroglobulin antibodies and only anti-mouse thyroglobulin antibodies in the spontaneous model were completely down-modulated by the drug. One surprising fact to emerge was that Linomide-treated donor mice, although protected from thyroid lesions themselves, were still able to transfer EAT showing that they must have been effectively primed while being treated with Linomide. It is possible that the drug down modulated EAT by interfering with the trafficking of primed effector cells.

Emotional dysfunction, child-family relationships and childhood atopic dermatitis

A link between atopic dermatitis (AD) and emotional dysfunction is now well established but consideration of this has yet to be widely incorporated into clinical management. A biopsychosocial model of the mind-body interaction is considered in conjunction with the theory of childhood emotional development and the impact of a diseased skin, for its effect on a child growing up with AD. AD inevitably adds to the difficulties of parenting, so that parents and children may become locked into dysfunctional relationships. This adds to the stresses for all concerned, and may contribute to the deterioration of the child's skin condition as part of a psychosomatic vicious cycle. There is a strong indication that the psychological dimensions of AD should be taken into account as part of routine management. Further research will be needed to establish the effectiveness of any psychological intervention.

Dose response of various radiation detectors to synchrotron radiation

Accurate dosimetry is particularly difficult for low- to medium-energy x-rays as various interaction processes with different dependences on material properties determine the dose distribution in tissue and radiation detectors. Monoenergetic x-rays from synchrotron radiation offer the unique opportunity to study the dose response variation with photon energy of radiation detectors without the compounding effect of the spectral distribution of x-rays from conventional sources. The variation of dose response with photon energies between 10 and 99.6 keV was studied for two TLD materials (LiF:Mg,Ti and LiF:Mg,Cu,P), MOSFET semiconductors, radiographic and radiochromic film. The dose response at synchrotron radiation energies was compared with the one for several superficial/orthovoltage radiation qualities (HVL 1.4 mm Al to 4 mm Cu) and megavoltage photons from a medical linear accelerator. A calibrated parallel plate ionization chamber was taken as the reference dosimeter. The variation of response with x-ray energy was modelled using a two-component model that allows determination of the energy for maximum response as well as its magnitude. MOSFET detectors and the radiographic film were found to overrespond to low-energy x-rays by up to a factor of 7 and 12 respectively, while the radiochromic film underestimated the dose by approximately a factor of 2 at 24 keV. The TLDs showed a slight overresponse with LiF:Mg, Cu, P demonstrating better tissue equivalence than LiF:Mg, Ti (maximum deviation from water less than 25%). The results of the present study demonstrate the usefulness of monoenergetic photons for the study of the energy response of radiation detectors. The variations in energy response observed for the MOSFET detectors and GAF chromic film emphasize the need for a correction for individual dosimeters if accurate dosimetry of low- to medium-energy x-rays is attempted.

Evaluation of trophoblast HLA-G antigen with a specific monoclonal antibody

A monoclonal antibody to HLA-G has been generated by immunizing HLA-A2.1/human beta 2-microglobulin (beta 2 m) double transgenic mice with murine L cells transfected with both human beta 2 m and HLA-G. This monoclonal antibody, designated as G233, has been found not to cross-react with other HLA class I antigens when tested on numerous cell lines by flow cytometry. With immunohistology, all populations of extravillous trophoblast (cell columns, interstitial trophoblast, endovascular trophoblast, placental bed giant cells) were stained. An extensive range of adult and fetal tissues was also tested but none reacted with monoclonal antibody G233, including those previously reported to express HLA-G mRNA, indicating that the protein has a highly restricted distribution. Failure to detect HLA-G in the fetal thymus raises the question as to how T-cell tolerance to this antigen is induced. Immunoprecipitation of trophoblast surface proteins with monoclonal antibody G233 revealed a heavy chain of 39 kDa and a light chain of 12 kDa, indicating that HLA-G expressed on the surface of trophoblast is complexed with beta 2 m. However, sequential immunoprecipitation with monoclonal antibody W6/32 followed by monoclonal antibody G233 continued to detect a residual band of 39 kDa, suggesting that trophoblast surface HLA-G may also occur as free heavy chains not associated with beta 2 m. Immunoprecipitation followed by two dimensional gel electrophoresis showed that monoclonal antibody G233 recognizes several isoforms of HLA-G from trophoblast similar to the characteristic spot array previously described for HLA-G. This monoclonal antibody G233 will be highly useful in future experiments to elucidate the function of HLA-G.

Aberrant TCR-mediated signaling in CD45-null thymocytes involves dysfunctional regulation of Lck, Fyn, TCR-zeta, and ZAP-70

CD45 is a transmembrane phosphotyrosine phosphatase expressed on all nucleated hemopoietic cells. Targeting of CD45 exon 9 has generated a mouse line completely lacking CD45 expression (CD45-null) in which there are severe abnormalities in T cell development. Defects in TCR-mediated signals underlying these abnormalities have now been investigated using CD45-null T cells. No T cell proliferation was detected in response to a CD3 mAb. In thymocytes the p56(lck) and p59(fyn) tyrosine kinases were hyperphosphorylated, and p56(lck) was in its inactive conformation. Both basal and TCR-stimulated tyrosine phosphorylation of TCR-zeta and CD3-epsilon were much reduced, and TCR stimulation induced an abnormal p18 phosphoisomer of TCR-zeta previously noted in T cells stimulated by altered peptide ligands. These defects were associated with the failure of ZAP-70 kinase recruitment to the TCR-zeta chain. TCR coupling to the tyrosine phosphorylation of several proteins, including HS1 and p120(cbl), was also much reduced. However, TCR-induced signaling was not ablated, and significant inositol phosphate and calcium signals were observed in CD45-null thymocytes. Our molecular analysis suggests that the threshold for TCR signal transduction is greatly increased in CD45-null T cells, thus explaining the profound defects in thymic development.

Aberrant TCR-mediated signaling in CD45-null thymocytes involves dysfunctional regulation of Lck, Fyn, TCR-zeta, and ZAP-70

CD45 is a transmembrane phosphotyrosine phosphatase expressed on all nucleated hemopoietic cells. Targeting of CD45 exon 9 has generated a mouse line completely lacking CD45 expression (CD45-null) in which there are severe abnormalities in T cell development. Defects in TCR-mediated signals underlying these abnormalities have now been investigated using CD45-null T cells. No T cell proliferation was detected in response to a CD3 mAb. In thymocytes the p56(lck) and p59(fyn) tyrosine kinases were hyperphosphorylated, and p56(lck) was in its inactive conformation. Both basal and TCR-stimulated tyrosine phosphorylation of TCR-zeta and CD3-epsilon were much reduced, and TCR stimulation induced an abnormal p18 phosphoisomer of TCR-zeta previously noted in T cells stimulated by altered peptide ligands. These defects were associated with the failure of ZAP-70 kinase recruitment to the TCR-zeta chain. TCR coupling to the tyrosine phosphorylation of several proteins, including HS1 and p120(cbl), was also much reduced. However, TCR-induced signaling was not ablated, and significant inositol phosphate and calcium signals were observed in CD45-null thymocytes. Our molecular analysis suggests that the threshold for TCR signal transduction is greatly increased in CD45-null T cells, thus explaining the profound defects in thymic development.

An independent check of treatment plan, prescription and dose calculation as a QA procedure

In many radiotherapy centres where planning for external beam treatments is performed by radiation therapists, the treatment sheet and its calculations are independently checked by staff from a different educational background, typically a radiotherapy physicist. The benefits of this practice were evaluated in a radiotherapy department with two linear accelerators, one combined superficial-orthovoltage unit and one telecaesium unit. Within the 19 months of the investigation period, 2328 checks were performed on the treatment sheets of 1579 patients. In six cases, errors in excess of 5% were detected, which if uncorrected, could potentially have affected local tumour control or caused normal tissue complications. It was found that an independent check of treatment sheets assists in keeping these errors as low as can be achievable in clinical practice, and suggests that treatment sheet checking and in vivo dosimetry play a complementary role in this aim. Independent treatment sheet checking is an important quality assurance (QA) activity, with additional advantages such as improved communication in the department, education of staff and in vivo dosimetry targeting. Therefore the advantages of the procedure seem to outweigh the additional workload of approximately 0.3 full-time staff per 1000 patients per year.

Defective depletion of CD45-null thymocytes by the Staphylococcus aureus enterotoxin B superantigen

The development of a normal T-cell repertoire is critically dependent on the negative and positive selection events which occur at the CD4+CD8+ (double positive, DP) stage of thymic development. Depending on the avidity of the T-cell antigen receptor (TCR) for peptides presented within the thymus, DP thymocytes are either positively selected for maturation to CD4+/CD8+ single positive cells or are depleted by apoptosis. The addition of superantigen to thymocytes within foetal thymic organ culture (FTOC) mimics the negative selection signal of potentially autoreactive thymocytes and induces the responding population of thymocytes to apoptose. Here we present evidence that the transmembrane phosphotyrosine phosphatase CD45 critically regulates TCR-induced signals in thymic differentiation and present data to show defective depletion of CD45-null transgenic TCR-Vbeta8 DP thymocytes in FTOC by the Staphylococcus aureus Enterotoxin B (SEB) superantigen.

Lipopolysaccharide binding proteins on polymorphonuclear leukocytes: comparison of adult and neonatal cells

We have previously shown that polymorphonuclear leukocytes (PMN) from cord blood of normal full-term infants have a decreased priming response to lipopolysaccharide (LPS) compared with PMN of adults. Because the reason for this difference is poorly understood, we compared LPS binding on PMN from adults and newborns by using a photoactivatable iodinated LPS (from Escherichia coli O111:B4), coupled to 2-(p-azidosalicylamido)-1,3'-dithopropionate (LPS-ASD) to covalently link LPS to the PMN membrane. We incubated 2 x 10(4) adult or neonatal PMN with 125I-ASD-LPS (100 ng/ml) together with unlabelled LPS (0 to 100,000 ng/ml) for 20 min at 4 degrees C. The maximum total 125I-ASD-LPS binding to newborn PMN (1,004 +/- 103 cpm) was lower than that binding to adult PMN (3,583 +/- 444 cpm; P < 0.01 with respect to newborn PMN). However, the concentration of unlabelled LPS that displaced 50% of the maximum specifically bound 125I-ASD-LPS was similar for PMN from adult and newborn infants (-4.85 +/- 0.04 and -5.13 +/- 0.14 log g of LPS per ml, respectively; P > 0.05). We further assessed the membrane binding of 125I-ASD-LPS to PMN by using membrane extracts analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. LPS binding proteins were found at approximately 73, 55 to 57, and 25 kDa in both adult and neonatal PMN. However, PMN from newborn infants had markedly lower membrane-associated 125I-ASD-LPS at the 55- to 57- and 25-kDa protein bands as indicated by the intensity of the autoradiograph. Binding of LPS at these bands was specific for the lipid A portion of LPS, since purified unlabelled lipid A displaced 125I-ASD-LPS in a dose-dependent manner. Thus, PMN from newborn infants bind less LPS than do PMN from adults, even though the sites for LPS membrane binding appear to be the same.

Radiotherapy treatment checking procedures throughout Australasia: results of a survey

In July 1995, a questionnaire was forwarded to thirty two physicists overseeing Radiation Oncology Departments and brachytherapy in hospitals throughout Australia and New Zealand. From the thirty seven hospitals reached by this survey, details were gathered on thirty hospitals, including the Newcastle Mater Hospital. In most radiotherapy centres where treatment planning is performed by radiation therapists, at least some of the treatment sheets and their calculations are double checked by radiotherapy physicists. While 23% checked the treatment sheets of all patients, in the majority of centres physicists were found to check only a minor selection, that is, less than 20% of all treatment sheets. Only in six centres physicists were not involved.

CD45-null transgenic mice reveal a positive regulatory role for CD45 in early thymocyte development, in the selection of CD4+CD8+ thymocytes, and B cell maturation

The CD45 transmembrane glycoprotein has been shown to be a protein phosphotyrosine phosphatase and to be important in signal transduction in T and B lymphocytes. We have employed gene targeting to create a strain of transgenic mice that completely lacks expression of all isoforms of CD45. The spleens from CD45-null mice contain approximately twice the number of B cells and one fifth the number of T cells found in normal controls. The increase in B cell numbers is due to the specific expansion of two B cell subpopulations that express high levels of immunoglobulin (IgM) staining. T cell development is significantly inhibited in CD45-null animals at two distinct stages. The efficiency of the development of CD4-CD8- thymocytes into CD4+ CD8+ thymocytes is reduced by twofold, subsequently the frequency of successful maturation of the double positive population into mature, single positive thymocytes is reduced by a further four- to fivefold. In addition, we demonstrate that CD45-null thymocytes are severely impaired in their apoptotic response to cross-linking signals via T cell receptor (TCR) in fetal thymic organ culture. In contrast, apoptosis can be induced normally in CD45-null thymocytes by non-TCR-mediated signals. Since both positive and negative selection require signals through the TCR complex, these findings suggest that CD45 is an important regulator of signal transduction via the TCR complex at multiple stages of T cell development. CD45 is absolutely required for the transmission of mitogenic signals via IgM and IgD. By contrast, CD45-null B cells proliferate as well as wild-type cells to CD40-mediated signals. The proliferation of B cells in response to CD38 cross-linking is significantly reduced but not abolished by the CD45-null mutation. We conclude that CD45 is not required at any stage during the generation of mature peripheral B cells, however its loss reveals a previously unrecognized role for CD45 in the regulation of certain subpopulations of B cells.

Workload and use factor of medical linear accelerators in radiotherapy

An important factor in the design of primary protective barriers is the use factor. The present study was aimed at obtaining historical data on the use factor of two dual modality linear accelerators in a radiotherapy department. Gantry angle, field size, and beam modifiers were recorded for all radiation qualities in use at two medical linear accelerators with 6 MV and 18 MV x-rays and multiple electron energies ranging from 4 MeV to 20 MeV. The data for one year of clinical use was extracted from a record and verifying system and an estimate of the physics workload on the machines was obtained by going through the quality assurance records and machine log books. Of the total dose of approximately 37,000 Gy delivered in one year at isocenter on each unit 80% was given as 6 MV x-rays. As can be expected, most x-ray beams were directed at the four cardinal gantry angles with the angular distribution for 6 MV and 18 MV x-rays being very similar. Electron fields were broadly distributed around the gantry pointing down position. Less than 25% of all clinical x-ray treatment fields extended beyond a field size of 200 cm2.

A perspex flattening filter for a 300k Vp orthovoltage X-ray beam

For economic reasons modern equipment which produces low to medium energy X-rays covers the whole range of beam qualities from traditional superficial to orthovoltage radiation qualities. A recent trend shows an increasing number of installations of orthovoltage units in the cancer therapy community in the last five years. The use of a single anode for accelerating voltages between 60 and 300 kVp leads to compromises with regards to beam flatness and symmetry in the anode/cathode direction of the Siemens Stabilipan II radiation beam. A perspex flattening filter was designed to improve these beam parameters of the 300 kVp radiation beam (HVT 4mm Cu) at 50 cm and 60 cm FSD using a diaphragm-mounted field defining device. The filter design correlates with focal spot characteristics of the beam. The use of the filter improves flatness and symmetry for all measured field sizes from 6 x 6 cm2 to 18 x 18 cm2 by up to 8% (flatness) and 7% (symmetry) respectively. No significant difference in the depth dose characteristic of the 300 kVp beam was found with and without the filter. The only modification in the planning procedures required is the use of an attenuation factor of 0.89 for the filter. The use of the filter improves the dose distribution in treatment of patients undergoing orthovoltage radiotherapy--in particular treatments with large field sizes such as for metastases in the spinal column.

Generation of an antibody to HLA-G in transgenic mice and demonstration of the tissue reactivity of this antibody

A method was devised to generate antibodies against the non-classical class I HLA-G antigen. This consisted of immunising HLA-A2/beta 2m double transgenic mice with HLA-G transfected into mouse Ltk- cells. A polyclonal antibody was obtained which appears to be specific for HLA-G. The staining pattern of this antibody was restricted solely to all populations of extravillous trophoblast. No fetal tissues reacted with this antibody, including those where HLA-G mRNA has been demonstrated, such as fetal eye, thymus and liver. This study confirms that HLA-G is a trophoblast-specific protein, although it remains a possibility that the technique of immunohistology is not sufficiently sensitive to detect low level HLA-G antigen expression in non-trophoblast tissues.

Deficient priming activity of newborn cord blood-derived polymorphonuclear neutrophilic granulocytes with lipopolysaccharide and tumor necrosis factor-alpha triggered with formyl-methionyl-leucyl-phenylalanine

Newborn infants are more susceptible to bacterial infections than adults. This susceptibility has been attributed to defects in humoral and cellular activity. Host cellular activity can be modified by factors produced by bacteria or the host in response to infection. We assessed the effect of two factors associated with gram-negative bacterial infection, lipopolysaccharide (LPS) and TNF-alpha, on polymorphonuclear neutrophilic granulocytes (PMN) obtained from adult or newborns (umbilical cord blood). PMN were primed in vitro with LPS (10 micrograms/L) or TNF-alpha (10(-9) M) for 45 min and then assessed, using a chemiluminescence (CL) assay as an indicator of oxidative radical production with formyl-methionyl-leucyl-phenylalanine as the trigger for CL initiation. CL activity of unprimed PMN was similar for adults and newborns (13.3 and 13.7 CL units, respectively). After priming with LPS, CL activity was increased to 43.4 CL units for PMN from adults but to only 17.6 CL units for PMN from newborns (p < 0.001, adults versus newborn increment). Priming of PMN with LPS was most effective when autologous plasma was present. Using FITC-conjugated LPS and a flow cytometry assay, we could demonstrate no difference between the binding affinity of LPS for adult and newborn PMN. However, formyl-methionyl-leucyl-phenylalanine binding studies indicated that adult PMN had a higher number of binding sites. TNF-alpha priming of newborn PMN was also ineffective. Adult PMN increased CL activity by 3.9-fold when primed with TNF-alpha, whereas newborn PMN increased by only 1.75-fold (p < 0.005). This priming deficiency was not attributable to TNF-alpha receptors because phycoerythrin-conjugated TNF-alpha was associated with PMN from adults and newborns equally. Thus, PMN from newborns are not primed effectively in vitro with LPS or TNF-alpha. This defect may contribute to neonatal susceptibility to bacterial infection.

Smooth muscle contractility and calcium channel density in hibernating and nonhibernating animals

Hibernating animals consistently survive prolonged periods of cold with body temperatures near the freezing point. Previous studies have suggested that regulation of calcium influx may be a fundamental cellular mechanism for cold tolerance in hibernating species. The present study was undertaken to compare (i) the calcium dependence of contractility and (ii) [3H]nitrendipine binding in homogenates of ileal longitudinal smooth muscle from the nonhibernating guinea pig (Cavia porcellus) and a hibernator, the ground squirrel (Spermophilus richardsonii). The contractility studies indicate that both the activation threshold for calcium and the concentration-response curve were shifted to the right in ground squirrel when compared with guinea pig. The binding site density in ground squirrel muscle was about an order of magnitude less than in guinea pig (Bmax = 10 +/- 2 (n = 12) and 86 +/- 6 fmol/mg protein (n = 5), respectively). These results indicate that ground squirrel tissues are less sensitive to external calcium and clearly have fewer calcium channels than the smooth muscle of the non-hibernator. The results continue to support the hypothesis that cold tolerance in hibernating species involves calcium homeostatic control mechanisms.

Subfractionation of cardiac sarcolemma with wheat-germ agglutinin

The properties of highly purified bovine cardiac sarcolemma subfractionated with the lectin, wheat-germ agglutinin (WGA) were studied. Two different membrane subfractions were isolated, one which was agglutinated in the presence of 1.0 mg of WGA/mg of protein (WGA+ vesicles) and a second fraction which failed to agglutinate (WGA- vesicles). These two membrane fractions had quantitatively different rates of Na+/K+-dependent, ouabain-sensitive ATPase and Na+/Ca2+ exchange activities, yet a similar protein composition, which suggests that they were both derived from the plasma membrane. WGA- vesicles had a decreased number of [3H]quinuclidinyl benzilate-binding sites and no detectable [3H]nitrendipine-binding sites. Electron-microscopic and freeze-fracture analysis showed that the WGA+ fraction was composed of typical spherical sarcolemmal vesicles, whereas the WGA- fraction primarily contained elongated tubular structures suggestive of the T-tubule vesicles which were previously isolated from skeletal muscle. Assays of marker enzymes revealed that these fractions were neither sarcoplasmic reticulum nor plasma membrane from endothelial cells. Moreover, WGA agglutination did not result in the separation of right-side-out and inside-out vesicles. On the basis of these findings we propose that the WGA+ fraction corresponds to highly purified sarcolemma, whereas the WGA- fraction may be derived from T-tubule membranes.