Place of radiotherapy for treatment of metastatic cervical, vaginal and endometrial uterine cancer

Beyond classical palliative-intent irradiation schemes, there are increasing data suggesting a benefit for intensive locoregional treatments in metastatic gynecological cancers. Such approach aims at avoiding local symptoms related to tumor progression, but may also improve survival outcome by shrinking tumor burden to a microscopic state. This strategy is rarely considered upfront (in highly selected patients with very limited oligometastatic disease), but rather after systemic treatment. In case of tumor response (especially if complete response) of the metastatic sites, pelvic±para-aortic radiotherapy can be considered in combination with a brachytherapy boost to obtain long-term local control, in particular in cervical or vaginal cancer patients. Such approach seems particularly relevant when there is isolated persistence or progression of macroscopic disease within the pelvis. In parallel, there is also an increasing place for radiotherapy of oligo-metastatic sites. We review the literature on the place of radiotherapy in the management of cancers of the cervix and metastatic endometrial cancer.

Validation externe des scores pronostiques de la Covid-19 en hospitalisation : une étude de cohorte multicentrique

Introduction

Patients et méthodes

Résultats

Conclusion

The Impact of Prior Season Vaccination on Subsequent Influenza Vaccine Effectiveness to Prevent Influenza-related Hospitalizations Over 4 Influenza Seasons in Canada

BACKGROUND

Recent studies have demonstrated the possibility of negative associations between prior influenza vaccines and subsequent influenza vaccine effectiveness (VE), depending on season and strain. We investigated this association over 4 consecutive influenza seasons (2011-2012 through 2014-2015) in Canada.

METHODS

Using a matched test-negative design, laboratory-confirmed influenza cases and matched test-negative controls admitted to hospitals were enrolled. Patients were stratified into 4 groups according to influenza vaccine history (not vaccinated current and prior season [referent], vaccinated prior season only, vaccinated current season only, and vaccinated both current and prior season). Conditional logistic regression was used to estimate VE; prior vaccine impact was assessed each season for overall effect and effect stratified by age (<65 years, ≥65 years) and type/subtype (A/H1N1, A/H3N2, influenza B).

RESULTS

Overall, mainly nonsignificant associations were observed. Trends of nonsignificant decreased VE among patients repeatedly vaccinated in both prior and current season relative to the current season only were observed in the A/H3N2-dominant seasons of 2012-2013 and 2014-2015. Conversely, in 2011-2012, during which B viruses circulated, and in 2013-2014, when A/H1N1 circulated, being vaccinated in both seasons tended to result in a high VE in the current season against the dominant circulating subtype.

CONCLUSIONS

Prior vaccine impact on subsequent VE among Canadian inpatients was mainly nonsignificant. Even in circumstances where we observed a trend of negative impact, being repeatedly vaccinated was still more effective than not receiving the current season's vaccine. These findings favor continuation of annual influenza vaccination recommendations, particularly in older adults.

CLINICAL TRIALS REGISTRATION

NCT01517191.

Novel DNMT3A germline mutations are associated with inherited Tatton-Brown-Rahman syndrome

Tatton-Brown-Rahman syndrome (TBRS) was recently described in 13 isolated cases with de novo mutations in the DNMT3A gene. This autosomal dominant condition is characterized by tall stature, intellectual disability and a distinctive facial appearance. Here, we report six cases of inherited TBRS caused by novel DNMT3A germline mutations. The affected individuals belong to two sib-ships: four from an Old Order Amish family in America and two from a French Canadian family in Canada. All of them presented with characteristic features of TBRS, including dysmorphic facial features, increased height, intellectual disability, and variable additional features. We performed clinical exome sequencing and identified two mutations in the DNMT3A gene, a c.2312G>A (p.Arg771Gln) missense mutation in the Amish family and a c.2296_2297delAA (p.Lys766Glufs*15) small deletion in the French Canadian family. Parental DNA analysis by Sanger sequencing revealed that the Amish mutation was inherited from the healthy mosaic father. This study reflects the first cases with inherited TBRS and expands the phenotypic spectrum of TBRS.

Molecular confirmation of nine cases of Cornelia de Lange syndrome diagnosed prenatally

OBJECTIVES

Cornelia de Lange syndrome (CdLS) is characterized by distinct facial features, growth retardation, upper limb reduction defects, hirsutism, and intellectual disability. NIPBL mutations have been identified in approximately 60% of patients with CdLS diagnosed postnatally. Prenatal ultrasound findings include upper limb reduction defects, intrauterine growth restriction, and micrognathia. CdLS has also been associated with decreased PAPP-A and increased nuchal translucency (NT). We reviewed NIPBL sequence analysis results for 12 prenatal samples in our laboratory to determine the frequency of mutations in our cohort.

METHODS

This retrospective study analyzed data from all 12 prenatal cases with suspected CdLS, which were received by The University of Chicago Genetic Services Laboratories. Diagnostic NIPBL sequencing was performed for all samples. Clinical information was collected from referring physicians.

RESULTS

NIPBL mutations were identified in 9 out of the 12 cases prenatally (75%). Amongst the NIPBL mutation-positive cases with clinical information available, the most common findings were upper limb malformations and micrognathia. Five patients had NT measurements in the first trimester, of which four were noted to be increased.

CONCLUSION

We demonstrate that prenatally-detected phenotypes of CdLS, particularly severe micrognathia and bilateral upper limb defects, are associated with an increased frequency of NIPBL mutations.

SU-E-T-25: Real Time Simulator for Designing Electron Dual Scattering Foil Systems

PURPOSE

To create a user friendly, accurate, real time computer simulator to facilitate the design of dual foil scattering systems for electron beams on radiotherapy accelerators. The simulator should allow for a relatively quick, initial design that can be refined and verified with subsequent Monte Carlo (MC) calculations and measurements.

METHODS

The simulator consists of an analytical algorithm for calculating electron fluence and a graphical user interface (GUI) C++ program. The algorithm predicts electron fluence using Fermi-Eyges multiple Coulomb scattering theory with a refined Moliere formalism for scattering powers. The simulator also estimates central-axis x-ray dose contamination from the dual foil system. Once the geometry of the beamline is specified, the simulator allows the user to continuously vary primary scattering foil material and thickness, secondary scattering foil material and Gaussian shape (thickness and sigma), and beam energy. The beam profile and x-ray contamination are displayed in real time.

RESULTS

The simulator was tuned by comparison of off-axis electron fluence profiles with those calculated using EGSnrc MC. Over the energy range 7-20 MeV and using present foils on the Elekta radiotherapy accelerator, the simulator profiles agreed to within 2% of MC profiles from within 20 cm of the central axis. The x-ray contamination predictions matched measured data to within 0.6%. The calculation time was approximately 100 ms using a single processor, which allows for real-time variation of foil parameters using sliding bars.

CONCLUSIONS

A real time dual scattering foil system simulator has been developed. The tool has been useful in a project to redesign an electron dual scattering foil system for one of our radiotherapy accelerators. The simulator has also been useful as an instructional tool for our medical physics graduate students.

Interobserver variability of croup scoring in clinical practice

BACKGROUND

Viral laryngotracheobronchitis croup is the most common cause of acute upper airway obstruction in young children. Clinical assessment of children with croup is often performed using 'croup scores'; however, these scores have not been validated outside of the research setting.

OBJECTIVE

To determine the reliability of clinical observation items in croup scores in a paediatric emergency department (ED) setting.

DESIGN

Literature review identified 12 observation items (level of consciousness or mental status, inspiratory breath sounds, air entry, stridor, cough, cyanosis or colour, anxiety or air hunger, retractions and/or flaring, respiratory rate and heart rate, oxygen saturation and respiratory distress); overlapping items were combined, yielding 10 variables. In a prospective cohort study over 13 months, patients presenting with croup were observed independently, and croup scores were assigned by the triage nurse, ED nurse and the ED physician before treatment. Agreement among observers for clinical observations was analysed using Cohen's quadratic weighted kappa.

SETTING

University-affiliated, paediatric hospital ED providing primary care to an urban area (population 330,000).

PATIENTS

Children aged three months to five years presenting with viral croup (preceding history of at least one day of upper respiratory tract symptoms associated with barking cough and/or hoarseness and/or stridor).

RESULTS

One hundred fifty-eight children meeting inclusion criteria for croup were assessed by three observers within 1 h of each other's assesments and before treatment. Interobserver agreement among the three observers using weighted kappa was greater than chance for all clinical observation items and ranged from fair to moderate (0.2 to 0.4 and 0.4 to 0.6, respectively).

CONCLUSIONS

In the busy practice setting of a paediatric ED, substantial interobserver variability exists among health care providers in the measurement of respiratory signs associated with croup in young children. Based on the present study in a practice setting and two research studies, the most reliable items of all of the published items included in croup scoring systems were stridor and retractions.

Cardiac risk assessment before the use of stimulant medications in children and youth

Regulatory decisions and scientific statements regarding the management of attention-deficit hyperactivity disorder (ADHD) raise questions about the safety of medications and the appropriate pretreatment evaluation to determine suitability for treatment with medication. This is particularly true in the setting of known structural or functional heart disease. The present paper reviews the available data, including peer-reviewed literature, data from the United States Food and Drug Administration Web site on reported adverse reactions in children using stimulant medication, and Health Canada data on the same problem. A consensus-based guideline on appropriate assessment is provided, based on input from members of the Canadian Paediatric Society, the Canadian Cardiovascular Society and the Canadian Academy of Child and Adolescent Psychiatry, with specific expertise and knowledge in the areas of both ADHD and paediatric cardiology. The present statement advocates a thorough history and physical examination before starting stimulant medications, with an emphasis on the identification of risk factors for sudden death, but does not routinely recommend electrocardiographic screening or cardiac sub-specialist consultation unless indicated by history or physical examination findings. A checklist for identifying children who are potentially at risk of sudden death (independent of ADHD or medications used to treat it) is provided. Although recommendations are based on the best evidence currently available, the committee further agrees that more research on this subject is necessary to optimize the approach to this common clinical scenario.

The small GTPase Cdc42 promotes membrane protrusion during polar body emission via ARP2-nucleated actin polymerization

Polar body emission is a specialized cell division throughout the animal kingdom, serving to reduce chromosome ploidy while preserving the egg cytoplasm. Critical to polar body emission are the asymmetric positioning of the meiotic spindle prior to anaphase, with one pole attached to the oocyte cortex, and the simultaneous membrane protrusion during subsequent cytokinesis. We have shown that, during Xenopus oocyte maturation, the small GTPase Cdc42 promotes membrane protrusion while a classical RhoA contractile ring forms and constricts at the base of the protrusion. We report here that treating oocytes with low concentrations of nocodazole diminished the size of metaphase I spindles and prevented polar body emission, and yet an active Cdc42 cap of correspondingly diminished size still developed, on time, atop of the spindle pole. Conversely, treating oocytes with low concentrations of taxol resulted in a spindle with multiple poles attached to the cortex, but still each of these poles were associated with activated cortical Cdc42 at the appropriate time. Therefore, the asymmetric positioning of the meiotic spindle with one pole anchored to the cortex is a prerequisite for Cdc42 activation. Furthermore, we demonstrated that the Cdc42-regulated F-actin nucleator ARP2/3 complex was similarly localized at the cortex of the protruding polar body membrane, suggesting that Cdc42 promotes membrane protrusion through an F-actin meshwork mechanism. Finally, we demonstrated that Cdc42 and RhoA formed similarly complementary activity zones during egg activation and that inhibition of Cdc42 prevented second polar body emission. Therefore, Cdc42 activation likely promotes membrane protrusion during polar body emission in widespread systems.

Fluoroquinolone resistance in renal isolates of Mycobacterium tuberculosis

SETTING

Alberta, Canada, 1990-2003.

OBJECTIVE

Monotherapy of active tuberculosis (TB) promotes drug resistance. Given the common practice of empiric fluoroquinolone (FQ) therapy for urinary tract infections (UTI) and frequent delayed diagnosis of renal TB, we assessed urine Mycobacterium tuberculosis isolates for FQ resistance.

DESIGN

Retrospective study. Urine M. tuberculosis isolates underwent FQ susceptibility testing. Records were reviewed for evidence of FQ exposure and diagnostic delay.

RESULTS

Among 78 culture-positive renal TB patients between 1990 and 2003, initial isolates of M. tuberculosis were available from 74 (94.9%). Three (4.1%) were FQ-resistant. Previous FQ use was confirmed in nine cases (12.2%). FQ-exposed isolates were more likely than non-exposed isolates to be FQ-resistant (2/9, 22.2% vs. 1/65, 1.5%, P = 0.037). Among 41 cases (55.4%) with signs or symptoms of UTI, eight (19.5%) had previous FQ exposure, of which seven (87.5%) had delayed diagnosis. Only 15/33 (45.5%) UTI symptomatic cases without prior FQ exposure had delayed diagnosis (P = 0.050). In 2/8 (25%) UTI symptomatic cases with prior FQ exposure, the M. tuberculosis isolate was FQ-resistant.

CONCLUSION

FQ monotherapy of unsuspected renal TB may delay diagnosis and lead to FQ resistance.

Effect of an integrated reality orientation programme in acute care on post-traumatic amnesia in patients with traumatic brain injury

PRIMARY OBJECTIVE

To assess the effect of an integrated reality orientation programme (North Star Project) in acute care on the duration of post-traumatic amnesia (PTA) of patients suffering from traumatic brain injury (TBI). It was hypothesized that those patients having participated in this programme would show a shorter PTA than those patients that did not.

METHOD

Duration of PTA for 12 patients with TBI who were part of the North Star Project was compared with that of 26 patients matched for initial GCS and age for whom this approach was not available (control group).

RESULTS

Length of PTA was shorter by 5 days for the North Star patients. This result was not statistically significant (p = 0.19) but is clinically relevant. No between-group difference was found for Glasgow Coma Scale.

CONCLUSIONS

Consequences of shorter PTA would include increased and more appropriate patient interaction and earlier transfer to rehabilitation. The North Star project also allows the family to become more actively involved in the treatment of their loved one. Further study is required to evaluate this intervention strategy to improve orientation for the patient with TBI.

Prediction of the level of cognitive functional independence in acute care following traumatic brain injury

PRIMARY OBJECTIVE

To determine a predictive model for cognitive functional outcome of patients with traumatic brain injury (TBI) at discharge from acute care.

METHODS AND PROCEDURE

Three hundred and thirty-five patients were included in this analysis. Variables considered were age, education, initial score on the Glasgow Coma Scale (GCS), duration of post-traumatic amnesia (PTA), cerebral imaging results and the need for neurosurgical intervention.

EXPERIMENTAL INTERVENTIONS

Functional Independence Measure (FIM).

MAIN OUTCOMES AND RESULTS

Results of this analysis indicated better cognitive FIM at discharge from acute care settings for patients with TBI when PTA was less than 24 hours, when level of education was higher, when no parietal lesion was identified, when no neurosurgical intervention was required, for patients with TBI who were younger and who presented with a higher GCS score upon admission.

CONCLUSIONS

This model will help to plan resource allocation for treatment and discharge planning within the first weeks following TBI.

Thermogenesis with relation to exercise and exercise-training

Exercise-training at environmental temperatures outside the thermal neutral zone, causes thermoregulatory adaptive reactions. In the heat, sweat efficiency is enhanced thus reducing the incidence of hyperthermia while in the cold discomfort and danger of frostbite are minimized by an improved cutaneous circulation specially in the extremities. Over long periods of time exercise does not affect thermogenesis except when refeeding. It is suggested that the reduced postprandial heat production reported in exercise-trained subjects is related to changes in nutrient metabolism which in turn could be related to insulin and norepinephrine modified actions.

Renal Transplantation in Children 15 Kg or Less: The British Columbia Children’s Hospital Experience

PURPOSE

Small infants are the most challenging group of patients to undergo renal transplantation.

PURPOSE

We reviewed the transplantation experience at our institution with children less than 15 kg at transplantation.

MATERIALS AND METHODS

We retrospectively reviewed the records of 24 recipients in a 20-year period. Technical and allograft outcomes were compared to those in the North American Pediatric Renal Transplant Cooperative Study database.

RESULTS

Since the inception of our program 24 recipients weighing 15 kg or less who were 6 years or younger have undergone transplantation. Seven grafts (29%) were from living donors. At transplantation mean age was 3.1 years (range 1.8 to 5.7) and mean weight was 13.4 kg (range 9.0 to 15.7). Average cold and warm ischemic times were 14.1 hours (range 3.4 to 37.2) and 23.1 minutes (range 21 to 41), respectively. Early complications were ureteral stricture requiring pyeloureterostomy in 1 case, reversible acute tubular necrosis in 2 and early arterial thrombosis salvaged by immediate thrombectomy in 1. Delayed complications were arterial stenosis requiring angioplasty in 2 cases, and 3 delayed deaths related to malignant hypertension in 2 and sepsis in 1. No grafts were lost due to thrombosis. Mean serum creatinine at years 1 to 3 and 5 were 48.5, 67.5, 79.1 and 84.4 mumol/l, respectively. Graft survival was 92% (22 patients after censoring 1 who died with a functioning graft) at 2 and 5 years. Overall results compare favorably to those in the North American Pediatric Renal Transplant Cooperative Study.

CONCLUSIONS

With a multidisciplinary team effort successful results can be achieved in this challenging group of patients.

High-energy resolution alpha spectrometry using cryogenic detectors

Applications such as environment monitoring implying alpha emitters activity measurement associated with isotope identification, require high-energy resolution detectors. Conventional silicon detectors are inexpensive therefore widely used, although intrinsically limited in energy resolution. Thermal detection principle of cryogenic detectors introduces a breakthrough in alpha particle measurement. For the first time, spectra with 5.5 keV FWHM energy resolution have been obtained for several external alpha emitting sources using a copper-germanium bolometer specially developed for alpha spectrometry.

Fitting the linear–quadratic model to detailed data sets for different dose ranges

Survival curve behaviour and degree of correspondence between the linear-quadratic (LQ) model and experimental data in an extensive dose range for high dose rates were analysed. Detailed clonogenic assays with irradiation given in 0.5 Gy increments and a total dose range varying from 10.5 to 16 Gy were performed. The cell lines investigated were: CHOAA8 (Chinese hamster fibroblast cells), U373MG (human glioblastoma cells), CP3 and DU145 (human prostate carcinoma cell lines). The analyses were based on chi2-statistics and Monte Carlo simulation of the experiments. A decline of LQ fit quality at very low doses (<2 Gy) is observed. This result can be explained by the hypersensitive effect observed in CHOAA8, U373MG and DU145 data and an adaptive-type response in the CP3 cell line. A clear improvement of the fit is discerned by removing the low dose data points. The fit worsening at high doses also shows that LQ cannot explain this region. This shows that the LQ model fits better the middle dose region of the survival curve. The analysis conducted in our study reveals a dose dependency of the LQ fit in different cell lines.

Oxidative stress regulated expression of Ubiquitin Carboxyl-terminal Hydrolase-L1: Role in cell survival

The ubiquitin Carboxyl-terminal Hydrolase-L1 gene (UCHL1) is a key enzyme in the protein degradation pathway; however, its precise role in protecting cells under stress conditions is unclear. In the present study we investigated the activity of this gene in human NT2/D1 embryonal carcinoma cells subjected to oxygen-glucose deprivation (OGD) and reoxygenation. OGD/reoxygenation cause global metabolic changes due to energy withdrawal and the subsequent generation of reactive oxygen species which initiates either a stress-adaptation-survival response or cell death, depending on the severity of the insult. A bi-phasic change in UCHL1 expression was observed by Q-PCR, Western blotting and flow cytometry. Down regulation of UCHL1 was detected immediately after OGD treatment and its expression was subsequently restored and increased 6 h after OGD treatment as well as during reoxygenation. Furthermore, flow cytometry analysis detected a lower level of UCHL1 only in apoptotic cells that had severe loss of mitochondrial membrane potential. Accordingly, down-regulation of endogenous UCHL1 by antisense cDNA in mouse N2a neuroblastoma cells increased the cell's sensitivity to OGD treatment. This down-regulation of endogenous UCHL1 led to the accumulation of p27, suggesting that UCHL1 is an essential gene to maintain cell homeostasis under normal growth and oxidative stress conditions.

Peak oxygen uptake and mortality in children with cystic fibrosis

BACKGROUND

Single measurements of peak oxygen uptake (VO2) have been shown to predict mortality in patients with cystic fibrosis (CF) although no longitudinal study of serial measurements has been reported in children. A study was undertaken to determine whether the initial, final, or the rate of fall of forced expiratory volume in 1 second (FEV1) or peak VO2 was a better predictor of mortality.

METHODS

Twenty eight children aged 8-17 years with CF performed annual pulmonary function and maximal exercise tests over a 5 year period to determine FEV1 and peak VO2, magnitude of their change over time, and survival over the subsequent 7-8 years. Analysis was done using Kaplan-Meier curves and Cox proportional hazard model.

RESULTS

Peak VO2 fell during the observation period in 70% of the patients, with a mean annual decline of 2.1 ml/min/kg. Initial peak VO2 was not predictive of mortality but rate of decline and final peak VO2 of the series were significant predictors. Patients with peak VO2 less than 32 ml/min/kg exhibited a dramatic increase in mortality, in contrast to those whose peak VO2 exceeded 45 ml/min/kg, none of whom died. The first, last, and rate of decline in FEV1 over time were all significant predictors of mortality.

CONCLUSIONS

Higher peak VO2 is a marker for longer survival in CF patients.

High-energy resolution X-ray, gamma and electron spectroscopy with cryogenic detectors

Cryogenic detectors offer remarkably better energy resolutions than those achievable with conventional semiconductor or scintillation detectors. With the additional asset of a detection efficiency close to unity for low-energy X-ray photons and electrons, these detectors have the potential to perform X-ray, gamma and electron spectroscopy of a hitherto unknown quality, in particular at low energies. Two types of cryogenic detectors are described and the results of prototype detectors are presented.

Dietary intakes and vitamin status of a sample of homeless people in Paris

OBJECTIVE

To determine nutritional intake and vitamin status in a sample of homeless people who had been on the streets of Paris for more than 2 y.

DESIGN

The nutritional status was evaluated by a 24 h recall questionnaire and by assay of circulating levels of vitamins A, B1, B6, B12, C and E.

SETTING

The study was conducted in four accommodation centres of the SAMU Social of Paris (CHUSI units) from July 1999 to May 2000.

SUBJECTS

A total of 329 homeless people were interviewed. Only 87 subjects, aged 26-76 y, were recruited based on seven selection criteria (over 18 y old, being homeless for more than 2 y, interviewed before taking a meal in the CHUSI units, good understanding of French, in a calm state, not coming from hospital or another CHUSI units, without any acute condition that might affect usual dietary habits), and completed the dietary questionnaire. Out of these 87, 71 agreed to blood sampling.

RESULTS

In all 84% of the subjects declared that they drank alcoholic beverages regularly (175+/-167 g/day of alcohol), and 75.5% of the subjects also declared that they smoked. The mean total energy intake was 2111+/-1482 kcal/day for the men (8823.98+/-6194.76 kJ/day) and 1523+/-531 kcal/day for the women (6366.14+/-2219.58 kJ/day). Alcohol accounted for 44+/-30% and 19+/-17% of the total energy intakes (TEI) for the men and women, respectively. Proteins, lipids and carbohydrates accounted for 21+/-9, 23+/-14 and 57+/-16%, respectively, of the energy intake without alcohol for men, and 15+/-5, 22+/-11 and 62+/-14% EIWA for women. For all micronutrients, except for iron in the men, more than 50% of the population studied had intakes below the French recommendations for the adult population. All the women had calcium, vitamin E and vitamin B1 intakes below the recommendations for French women (900, 12 and 1.3 mg/day, respectively) in the general population. For the men, 98.7, 96.1 and 93.5% of the subjects had vitamin E, B1 and C intakes below the recommendations for French males in the general population (12, 1.5 and 80 mg/day, respectively). It is of note that subjects who ate in the CHUSI units more than once a day per week had significantly (P=0.018) higher intakes of vitamin C (27+/-38 mg/day) than did the subjects who ate in the CHUSI units less than once a day (8+/-12 mg/day). Measurement of serum vitamin levels demonstrated a deficiency in 95% of the subjects, mainly for vitamin C. The mean concentration in serum was 16+/-8 micromol/l, although 72% of the subjects had levels of 6 micromol/l. In contrast, 50.7, 42.2 and 35.2% of the subjects had high levels of vitamin B6, B12 and B1, respectively (100 nmol/l, 420 pmol/l and 40 micromol/l).

CONCLUSION

Alcohol takes a high place in the diet of these homeless people. Although the total energy intake was too low, macronutrient intakes seem to be satisfactory in quality (well-balanced). However, calcium and vitamin C intakes were too low, and these deficiencies favour the development of disease (scurvy, asthenia, ecchymosis), in addition to alcohol-linked disease. Furthermore, the overexposure to vitamin B6, among the other B vitamins, is a matter of concern since it has been shown to be toxic in high doses.

A new absolute method for the standardization of radionuclides emitting low-energy radiation

Microcalorimeters (or bolometers) operated at temperatures below 100 mK allow individual counting of photons and electrons with a very low energy detection threshold. The physics is based on the pulse temperature increase of the target (or absorber) of the detector due to the complete absorption of both electrons and photons. Since this target can be constructed with a perfect 4-pi geometry, a bolometer offers potentially a new method for absolute activity measurements of radionuclides emitting low-energy radiation. In this paper we present our first results of a feasibility study of activity standardization of a 55Fe solution with a prototype 4-pi bolometer.

Neither caspase-3 nor DNA fragmentation factor is required for high molecular weight DNA degradation in apoptosis

In this paper, we show that there is a two-step process of DNA fragmentation in apoptosis; DNA is first cleaved to large fragments of 50-300 kb that are subsequently cleaved to smaller oligonucleosomes in some, but not all cells. Significantly, only the first stage is considered essential for cell death since some cells, for example human MCF7 breast carcinoma cells and human NT2 neuronal cells, do not show this behavior but still display normal nuclear morphological apoptotic changes. In cells that usually produce small fragments blocking the second (internucleosomal) stage of DNA fragmentation prevents neither nuclear condensation nor apoptosis. We are beginning to understand why the extent of DNA fragmentation during apoptosis varies enormously and why it appears to be a function of the cell type not the inducer. Presumably, this reflects the content of not only endonuclease activit(ies) but also on the ability of the cells to activate caspases, particularly caspase-3, and other proteases that may be involved in endonuclease activation. Since NT2 cells activate caspase-3, but do not correctly process DFF45, other factors must also impinge on the inevitability of that process.

Detection of DNA fragmentation and endonucleases in apoptosis

DNA degradation during apoptosis is endonuclease mediated and proceeds through an ordered series of stages commencing with the production of large DNA pieces of 300 kb which are then degraded to fragments of 50 kb. The 50-kb fragments are further degraded, in some but not all cells, to smaller pieces (10-40 kb) releasing the small oligonucleosome fragments that are detected as a characteristic DNA ladder on conventional agarose gels. Methodology is presented for the detection of both DNA ladders and the initial stages of DNA fragmentation using pulsed-field gel electrophoresis. We have developed electrophoresis conditions that resolve large fragments of DNA and also retain the smaller fragments on the same gel. Methods for the detection of endonuclease activities responsible for the cleavage of DNA during apoptosis are also presented.

Protein meals and postprandial thermogenesis

In North America the consumption of meat far exceeds that of fish. Because the palatability of the food has been shown to influence the thermogenic response to feeding, a study was designed to compare the metabolic response to 195-g beef steak and 250-g cod fillet containing both 43 g of proteins in a first experiment and to 250 g of both nutrients in a second experiment. The subjects who participated in this study gave a higher rating of palatability (obtained on a 10-cm visual analog scale) when the beef steak (7.4) was consumed compared to the cod fillet (3.0). Measurements of oxygen consumption during the cephalic phase (0 to 40 min) indicated a larger thermogenic response to the beef than to the fish meal. These findings suggest that the thermic response to feeding during the cephalic phase are related to the sensory stimulation of the meal. During the gastrointestinal phase (40 to >180 min) the response was not influenced by the type of food and was related instead to the amount of proteins ingested. Plasma amino acid determinations indicated differences between the beef and fish feeding. Plasma histidine and glutamine was higher after beef feeding. The meaning of these findings does not seem to be related at this time to the results obtained on postprandial thermogenesis. The increases in plasma insulin that were observed during both phases of feeding were similar for the beef and the fish meals. Despite a marked increase of insulin, plasma glucose remained unchanged after feeding either meals, suggesting an enhanced gluconeogenesis and an increased glucose utilization.

Pediatricians' experience of ethical dilemmas in practice: implications for education

OBJECTIVE

To determine Canadian pediatricians' experience with ethical dilemmas, to relate this information to proposed curriculum for residency training in Canada, and to determine pediatricians' self-assessment of adequacy of training in ethical issues and the means used in practice to resolve dilemmas.

METHOD

A single-pass questionnaire was mailed to all 1,220 pediatrician members of the Canadian Pediatric Society.

RESULTS

From the 363 questionnaires (30 per cent) that were returned, 43 per cent of respondents had received formal ethics education in their training. Approximately half of respondents judged their training as adequate. Responses confirmed the themes of futile treatment, demands for and refusal of treatment by parents, uncertainty regarding withdrawing or withholding treatments, conflicts over judgments about the right thing to do, and dilemmas regarding the role of the child and adolescent. Respondents relied mainly on informal discussion with colleagues to resolve their dilemmas in practice.

CONCLUSIONS

Core residency and continuing physician education need a valid epidemiological description of ethical issues encountered in practice. Educational approaches to the development of ethical knowledge, skills, and attitudes must be validated as there is a tendency to rely on case precedent and peer judgment. Perceived competence in handling ethical issues and dilemmas must be tested against accepted standards. Emerging ethical issues such as resource allocation, peer review, managed care, and technological and scientific advances must be regularly incorporated into both residency education and continuing medical education.

Metabolic and hormone-related responses to caffeine in rats

The time course of effects of caffeine on plasma glucose and non-esterified fatty acids (NEFA) were measured and related to various hormonal responses associated with substrate mobilization and utilization. Participation of the sympatho-adrenal system (SAS) in the metabolic and hormonal actions of caffeine was also investigated by the use of ganglionic blockade. Following 50 mg kg-1 i.p. injections of caffeine in rats, plasma glucose increased 25% and NEFA 40%, and these actions were parallelled by an elevation of plasma insulin, ACTH and corticosterone, without changes in glucagon. It is suggested that the insulin response is related to the plasma glucose increase and possibly also to an action of cAMP. When caffeine was injected in rats previously treated with the ganglionic blocker, hexamethonium, none of the responses mentioned above were modified. These results show that the glucose and NEFA responses are independent of glucagon secretion and are due not only to SAS activation but also to other mechanisms such as the increased ACTH and corticosterone secretion. It is also suggested that the mobilization of substrates by caffeine is mediated, through these various mechanisms, by the activation of cAMP and by phosphodiesterase inhibition.

[Association between depression, temperament and personality disorder: some therapeutic implications]

Certain personality traits or disorders in combination with clinical signs complicate the diagnosis and treatment of depression. The approaches to the relationships between personality and mood disorders vary. Some see important links between normal personality types (or temperaments) and depression, while others see certain temperaments as sub-syndromic variants of mood disorders. Finally, a third approach proposes an analysis, drawing on Robins and Guze's criteria, of the validity of psychiatric diagnoses for determining whether this frequent comorbidity of depression and personality disorders (DSM-III) is consistent with a nosologic relationship, or is merely some definitional or other artefact. A category-based diagnostic approach provides little clarification; in some studies, a dimensional model attempts to better define the links between depression, temperament and personality and clarify the content of the apparently heterogeneous notion of depression, with therapeutic implications. Research in this area should lead to the development of increasingly specific therapeutic approaches to depression.

The effect of caffeine on food intake in rats: involvement of corticotropin-releasing factor and the sympatho-adrenal system

The involvement of CRH and the sympatho-adrenal system in the effects of caffeine on food intake and body weight gain has been investigated in rats. Food intake and body weight gain were measured in male rats after the treatment with caffeine in combination with either an injection of the CRH antagonist alpha-helical CRH(9-41), a surgical adrenal demedullation (medullectomy), or a ganglionic blockade. Alpha-helical CRH(9-41) was injected in the lateral ventricle of the brain and hexamethonium was used to chemically block the ganglionic transmission. From 4 to 24 h following a caffeine injection, spontaneous food intake, which was cumulated from the time caffeine was injected, was significantly (p < 0.01) lower in caffeine- than in saline-treated rats. In food-deprived rats, the anorectic effect of caffeine was biphasic, being significant at 0.5 and 1 h after the caffeine administration, then vanishing for 3 h, and becoming significant again 6 h after the caffeine administration. In both the spontaneously fed and food-deprived rats, caffeine reduced the rate of weight gain, which was measured at the end of a 12- or a 24-h period following the caffeine injection. A significant (p < 0.05) interaction effect of caffeine and alpha-helical-CRH(9-41) was found on the cumulative food intake at 1, 6, and 8 h, and on the amount of food eaten between the 4-6-h interval following the injection of caffeine; the effects of caffeine on food intake and body weight gain seem largely prevented by the use of a CRH antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Descending aortic blood flow velocity as a noninvasive measure of cardiac output in children

In previous work, we postulated that mean aortic flow velocity (MAFV) might be a direct measure of cardiac index. To investigate the assumptions inherent in this relation, we measured body surface area, aortic cross-sectional area (two-dimensional ultrasonography) and MAFV (Doppler ultrasonography) in 70 normal children. For a direct check of the relation, we simultaneously measured cardiac index (Fick technique) and MAFV (Doppler ultrasonography) in 25 children after cardiac surgery. In the normal group, we found that body surface area was directly proportional to aortic cross-sectional area (R 0.94), and MAFV at rest was the same in the ascending and descending aorta (t test, p < 0.05). In the intensive care patients, MAFV in the descending aorta was directly proportional to cardiac index over a wide clinical range [MAFV (cm/s) = CI (L/min/m2).7.7-1.2]. The assumptions made when deriving the relation between MAFV and cardiac index appear to be valid whether measured in the ascending or descending aorta. However, the scatter of results limits its clinical value. Mean aortic flow velocity is probably of greater use as a trend indicator and has the potential for continuous display using an esophageal Doppler probe when measured in the descending aorta.

Relationship between apoptosis and the cell cycle in lymphocytes: roles of protein kinase C, tyrosine phosphorylation, and AP1

The mechanism of switching between the cell cycle and active cell death (apoptosis) was investigated in cytokine-dependent CTLL cells. These cells proliferate in the presence of interleukin 2 (IL2), but accumulate in early G1 and undergo apoptosis in its absence. In the absence of IL2 the cells also become sensitive to glucocorticoid-induced apoptosis. Using specific inhibitors of protein kinase C and tyrosine kinases we established that two signals are required to fully repress cell death and stimulate G1 progression. One of these signals activates protein kinase C (PKC) which represses cell death and the other activates a tyrosine kinase which confers glucocorticoid resistance and permits cell cycle progression. Thus, phorbol esters can activate PKC and maintain cell viability in the absence of IL2, but the cells cannot proliferate. Moreover, the cells remain sensitive to glucocorticoid-induced apoptosis unless the tyrosine kinase-mediated signal is also given. There is a correlation between the presence of AP1 DNA-binding activity and the repression of the cell death pathway. The c-jun gene is expressed constitutively and both IL2 and phorbol esters induce the expression of c-fos to generate a functional AP1 capable of repressing cell death. However, only interleukin 2 can initiate the tyrosine kinase-mediated modification that confers dexamethasone resistance and permits G1 progression. In the absence of IL2 glucocorticoids stimulate AP1 degradation and induce apoptosis.

Effects of fasting and food restriction on sympathetic activity in brown adipose tissue in mice

The activity of the sympathetic nervous system in mice that were either fed ad libitum, food restricted or fasted was estimated by measuring the accumulation of dopamine following the inhibition of dopamine beta-hydroxylase activity. Mice in each group were injected with the dopamine beta-hydroxylase inhibitor 1-cyclohexyl-2-mercaptoimidazole and were exposed to either 30 degrees C (warm) or 4 degrees C (cold). Mice were killed 1 h after the injection. Both heart and brown adipose tissue were then quickly removed and homogenized in ice-cold perchloric acid. Dopamine and noradrenaline were determined using high performance liquid chromatography. Regardless of whether mice were warm or cold exposed, both content and concentration of brown adipose tissue and dopamine were predictably higher in 1-cyclohexyl-2-mercaptoimidazole-injected mice than in non-injected animals. In mice fed ad libitum, post-injection content and concentration of dopamine in both brown adipose tissue and heart were higher in cold-exposed mice than in warm-exposed animals. In food-restricted and fasted mice, post-injection concentrations of dopamine in brown adipose tissue were higher in cold-exposed mice than in warm-exposed animals. In food-restricted and fasted mice there was no difference between warm- and cold-exposed animals with respect to post-injection contents and concentrations of dopamine in heart tissue. In fasted mice there was no difference between warm- and cold-exposed animals in post-injection content of dopamine in brown adipose tissue. This study provides further evidence that fasting, in contrast to food restriction, may blunt the tissue sympathetic nervous system response in brown adipose tissue of cold-exposed mice.

The topoisomerase II inhibitor teniposide (VM-26) induces apoptosis in unstimulated mature murine lymphocytes

This study shows that not only concanavalin A-stimulated proliferating lymphocytes but also unstimulated mouse splenic lymphocytes are sensitive to the topoisomerase II (topo II) inhibitor teniposide (VM-26). When unstimulated lymphocytes are pretreated with VM-26 for a 2-h period and are then incubated in drug-free medium, cell viability, as determined by trypan blue exclusion, decreases to 40% of the control by 6 h. The drug-treated cultures show two to three times the level of detergent soluble DNA than the control cultures and agarose gel electrophoresis of the soluble DNA shows the presence of oligonucleosomal-sized fragments, a feature considered to be a hallmark of apoptosis. Phase contrast microscopy, Hoechst staining for DNA, and immunofluorescence microscopy of various nuclear and cytoplasmic antigens (nucleolar fibrillarin, snRNP, ubiquitin, vimentin, tubulin) in the VM-26-treated cells characterize the morphological changes during apoptosis of these cells. The role of topo II as the mediator of the VM-26 effects is supported by pulsed field gel electrophoresis, which shows the typical topo II-induced cleavage of supercoiled DNA into loop-sized 300- and 50-kbp fragments. We conclude that the cancer chemotherapeutic agent VM-26 interacts with topo II and induces apoptosis in unstimulated lymphocytes.

The involvement of the sympathetic nervous system in meal-induced thermogenesis in mice

The acute effect of food intake on the activity of the sympathetic nervous system (SNS) in both heart and brown adipose tissue (BAT) was investigated in mice. Upon delivery to the laboratory mice were housed singly and divided into two groups. Half the mice were accustomed to eat their daily food ration in two meals whereas the other half were given continuous access to food. SNS activity in both heart and BAT was estimated by measuring the accumulation of dopamine (DA) after having blocked the transformation of dopamine into noradrenaline (NA) with 1-cyclohexyl-2-mercapto-imidazole (CHMI). CHMI inhibits the enzyme dopamine beta-hydroxylase. On the day SNS activity was assessed, continuously fed (CF) or meal-fed (MF) mice were injected with either saline or CHMI one hour before being killed. In order to assess the anticipatory effects of being fed, a group of mice already accustomed to the meal-feeding schedule were not allowed to eat after the injections. Additional CF and MF mice were killed without being injected in order to determine the basal levels of both DA and NA. The results show that the accumulation of DA in both heart and BAT was higher in MF than CF mice regardless of whether MF mice were or were not fed after the injection of CHMI. It therefore appears that the intake of food may increase SNS activity in various tissues in mice, and that such a response may be largely of cephalic origin.

Topoisomerase II-reactive chemotherapeutic drugs induce apoptosis in thymocytes

The effects of topoisomerase II-reactive epipodophyllotoxins etoposide and teniposide as well as amsacrine on the viability of thymocytes in primary culture has been examined. All three drugs were shown to produce DNA cleavage detectable by resolving isolated DNA by pulsed field agarose gel electrophoresis. The DNA cleavage was found to have two components. The first was due to the interaction of the drugs with topoisomerase II, whereas the second component was due to endonuclease cleavage caused by the drug-induced entry of the thymocytes into programmed cell death or apoptosis. This second component of the DNA cleavage was also detected in thymocytes undergoing apoptosis following exposure to the glucocorticoid analogue, dexamethasone. The effect of the drugs on programmed cell death is dependent upon new protein and RNA synthesis, indicating that topoisomerase II has a role in the very first stages of the process. These results are discussed in terms of the use of this class of topoisomerase II-reactive drugs in chemotherapy.

Periodicity of DNA folding in higher order chromatin structures

Each level of DNA folding in cells corresponds to a distinct chromatin structure. The basic chromatin units, nucleosomes, are arranged into solenoids which form chromatin loops. To characterize better the loop organization of chromatin we have assumed that the accessibility of DNA inside these structures is lower than on the outside and examined the size distribution of high mol. wt DNA fragments obtained from cells and isolated nuclei after digestion with endogenous nuclease or topoisomerase II. The largest discrete fragments obtained contain 300 kbp of DNA. Their further degradation proceeds through another discrete size step of 50 kbp. This suggests that chromatin loops contain approximately 50 kbp of DNA and that they are grouped into hexameric rosettes at the next higher level of chromatin structure. Based upon these observations a model by which the 30 nm chromatin fibre can be folded up into compact metaphase chromosomes is also described.

Factors affecting cold acclimation and thermogenesis in man

Three types of cold exposure are observed in man: systemic moderate cold (SM), systemic severe cold (SS), and local severe cold (LS). Contrary to rat, prolonged exposure to SM cold does not produce non-shivering thermogenesis, as it does in the rat, possibly because of lack of active brown adipose tissue. Instead there is a reduction in heat production, in shivering, and in discomfort through a process known as habituation. No adaptation was found with exposure to SS cold, since shivering and discomfort always prevail and there is indirect evidence of enhanced sympathetic response after repeated exposure to SS cold. Exposure to LS cold leads to adaptive responses in which discomfort and autonomic activity are reduced. It is suggested that LS adaptation is also related to habituation.