Synergies between Fibrillated Nanocellulose and Hot-Pressing of Papers Obtained from High-Yield Pulp

To extend the application of cost-effective high-yield pulps in packaging, strength and barrier properties are improved by advanced-strength additives or by hot-pressing. The aim of this study is to assess the synergic effects between the two approaches by using nanocellulose as a bulk additive, and by hot-pressing technology. Due to the synergic effect, dry strength increases by 118% while individual improvements are 31% by nanocellulose and 92% by hot-pressing. This effect is higher for mechanical fibrillated cellulose. After hot-pressing, all papers retain more than 22% of their dry strength. Hot-pressing greatly increases the paper's ability to withstand compressive forces applied in short periods of time by 84%, with a further 30% increase due to the synergic effect of the fibrillated nanocellulose. Hot-pressing and the fibrillated cellulose greatly decrease air permeability (80% and 68%, respectively) for refining pretreated samples, due to the increased fiber flexibility, which increase up to 90% using the combined effect. The tear index increases with the addition of nanocellulose, but this effect is lost after hot-pressing. In general, fibrillation degree has a small effect which means that low- cost nanocellulose could be used in hot-pressed papers, providing products with a good strength and barrier capacity.

Lignin Inter-Diffusion Underlying Improved Mechanical Performance of Hot-Pressed Paper Webs

Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing temperature of 270 °C. The stronger bonding of wet fibres can be explained by the inter-diffusion of lignin macromolecules with an activation energy around 26 kJ mol^-1 after lignin softening. The associated exponential acceleration of diffusion with temperature dominates over other factors such as process dynamics or final material density in setting wet strength. The optimum pressing temperature for dry strength is generally lower, around 200 °C, beyond which hemicellulose degradation begins. By varying the solids content prior to hot-pressing for the TMP sheets, the highest wet strength is achieved for the completely dry web, while no strong correlation was observed for the dry strength.

Heavy metal content of Swedish municipal wastewater sludge - status and goals

In 2014, 25% of the sludge produced at Swedish municipal wastewater treatment plants was applied to agricultural land. Even though the Swedish heavy metal limits for sludge to be used in agriculture are amongst the most stringent in the EU, more stringent heavy metal limits are proposed. Most sludge applied to agricultural land is recycled within a certification system, Revaq. Revaq has targets for control at source management and improvement of sludge quality. Statistics based on data collected within the Revaq system was used to differentiate between local and general sources of heavy metals and assess the need to improve sludge quality. The analysis indicates that proposed future national limits on the quality of the sludge can be met by most of the sludge. The improvement needed for about 20% of the sludge is feasible through local control at source management. The levels of cadmium, copper and mercury need to be reduced if these metals are not to limit the amount of sludge that may be applied per unit area of arable land. Finally, the long term Revaq targets for cadmium and silver will be difficult to meet.

Time-dependent breakdown of fiber networks: Uncertainty of lifetime

Materials often fail when subjected to stresses over a prolonged period. The time to failure, also called the lifetime, is known to exhibit large variability of many materials, particularly brittle and quasibrittle materials. For example, a coefficient of variation reaches 100% or even more. Its distribution shape is highly skewed toward zero lifetime, implying a large number of premature failures. This behavior contrasts with that of normal strength, which shows a variation of only 4%-10% and a nearly bell-shaped distribution. The fundamental cause of this large and unique variability of lifetime is not well understood because of the complex interplay between stochastic processes taking place on the molecular level and the hierarchical and disordered structure of the material. We have constructed fiber network models, both regular and random, as a paradigm for general material structures. With such networks, we have performed Monte Carlo simulations of creep failure to establish explicit relationships among fiber characteristics, network structures, system size, and lifetime distribution. We found that fiber characteristics have large, sometimes dominating, influences on the lifetime variability of a network. Among the factors investigated, geometrical disorders of the network were found to be essential to explain the large variability and highly skewed shape of the lifetime distribution. With increasing network size, the distribution asymptotically approaches a double-exponential form. The implication of this result is that, so-called "infant mortality," which is often predicted by the Weibull approximation of the lifetime distribution, may not exist for a large system.

Time-dependent statistical failure of fiber networks

Numerical simulations of time-dependent stochastic failure of fiber network have been performed by using a central-force, triangular lattice model. This two-dimensional (2D) network can be seen as the next level of structural hierarchy to fiber bundles, which have been investigated for many years both theoretically and numerically. Unlike fiber bundle models, the load sharing of the fiber network is determined by the network mechanics rather than a preassigned rule, and its failure is defined as the point of avalanche rather than the total fiber failure. We have assumed that the fiber in the network follows Coleman's probabilistic failure law [B. D. Coleman, J. Appl. Phys. 29, 968 (1958)] with the Weibull shape parameter β=1 (memory less fiber). Our interests are how the fiber-level probabilistic failure law is transformed into the one for the network and how the failure characteristics and disorders on the fiber level influence the network failure response. The simulation results showed that, with increasing the size of the network (N), weakest-link scaling (WLS) appeared and each lifetime distribution at a given size approximately followed Weibull distribution. However, the scaling behavior of the mean and the Weibull shape parameter clearly deviate from what we can predict from the WLS of Weibull distribution. We have found that a characteristic distribution function has, in fact, a double exponential form, not Weibull form. Accordingly, for the 2D network system, Coleman's probabilistic failure law holds but only approximately. Comparing the fiber and network failure properties, we found that the network structure induces an increase of the load sensitivity factor ρ (more brittle than fiber) and Weibull shape parameter β (less uncertainty of lifetime). Superimposed disorders on the fiber level reduce all these properties for the network.

Cholinergic denervation attenuates phencyclidine-induced c-fos responses in rat cortical neurons

The cortical cholinergic innervation, which is important for memory and cognition, has been implicated in schizophrenia. To experimentally analyze such a possible role of the cholinergic system, we have used the dissociative drug phencyclidine (PCP), known to produce schizophrenia-like psychosis in humans, to model aspects of schizophrenia in rats. We previously showed that induced cortical cholinergic hypofunction leads to enhanced PCP-induced locomotor activity and attenuated social interaction. After PCP, rats lacking cortical cholinergic innervation also show impaired declarative memory. To directly study the role of the basalo-cortical cholinergic projections for PCP-induced neural activation in different cortical areas, we have now monitored the rapid (30 and 60 min) effects of low doses of PCP (2 and 3mg/kg) on neural activation as reflected by transcriptional activation of c-fos in cortical areas, using quantitative in situ hybridization. We find an almost pan-cortical neural induction of c-fos mRNA with doses of PCP low enough not to alter levels of either BDNF or Nogo receptor mRNA levels. Specific unilateral lesioning of the uncrossed cholinergic projections to the cortical mantle by 192-IgG-saporin immunotoxin delivery to nc basalis (NBM) caused a striking ipsilateral decrease of the PCP-induced cortical c-fos mRNA induction, restricted to areas which had become effectively denervated. Because PCP at low doses is unlikely to directly influence cortical neurons, we suggest that it acts by activation of the cholinergic input, which in turn leads to cortical c-fos mRNA increases. Our results are compatible with a role for the cholinergic system in symptoms of schizophrenia, by showing that the basalo-cortical cholinergic projections are needed in order for PCP to have full activating effects on cortical neurons.

A strategy for reducing pollutants at source in order to obtain sustainable agricultural recycling of wastewater sludge

The Swedish licensing system for wastewater sludge use in agriculture, REVAQ, sets challenges. These include a maximum nominal accumulation rate of 0.2%/year on farmland, for specified metals, to be reached by 2025. Here a model is suggested, and applied for the Gothenburg regional wastewater treatment plant, Gryaab, to quantify historic sludge quality improvements and necessary future development. Local sampling campaigns covering two decades show a substantial reduction of heavy metals and ecologically harmful organic substances (such as adsorbable organic halogens, nonylphenols, phthalates, naphthalenes and polycyclic aromatic hydrocarbons) from households and society at large. For the metals studied the historic mass flow reduction to sludge varies from 1 to 2%/year for mercury, zinc and copper to 15%/year for silver. Copper needs further reduction, involving water pipes and copper roofing. Silver is rare in soil, and significant reduction from already low levels is needed to reach the accumulation goal. Further reduction of other metals involves addressing storm- and drainage water entering the sewers and the sediments already in the sewers. Fulfilling the goals of REVAQ implies national and local measures affecting public and private stakeholders including property owners, the wastewater collection system, commercial businesses and legislating authorities.

Retention and maternal transfer of brominated dioxins in zebrafish (Danio rerio) and effects on reproduction, aryl hydrocarbon receptor-regulated genes, and ethoxyresorufin-O-deethylase (EROD) activity

Brominated dioxins have recently been detected in Baltic Sea biota. Due to their similarities to the highly toxic chlorinated dioxins, concern has been raised about their potential biological effects. The present study investigated retention and effects of brominated dioxins in adult zebrafish, as well as maternal transfer and effects on offspring. We exposed adult zebrafish for nine weeks via feed to 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) or to a mixture of brominated dioxins (Baltic Sea mixture), which was designed to reflect relative concentrations found in Baltic Sea biota. We studied spawning success, gonad morphology, hepatic vitellogenin gene expression, and offspring early life-stage development to investigate effects on zebrafish reproduction. Hepatic ethoxyresorufin-O-deethylase (EROD) activity and hepatic expression of a number of aryl hydrocarbon receptor (AHR)-regulated genes were studied to investigate if the brominated dioxins can activate gene transcription through the AHR pathway in zebrafish. In addition, glutathione reductase activity and expression of genes involved in adaptive responses to intracellular stress were studied to investigate potential stress effects of brominated dioxins. After nine weeks of exposure, all brominated dioxins spiked to the feed were detected in female fish and transferred to eggs. Exposure to the Baltic Sea mixture and TBDD clearly induced AHR-regulated genes and EROD activity. Exposure to TBDD reduced spawning success, altered ovarian morphology and reduced hepatic vitellogenin gene expression, which implies that TBDD has a similar effect pattern as the chlorinated analogue. Overall, our results show that dietary exposure to sublethal concentrations of brominated dioxins may impair reproductive physiology in fish and induce AHR-regulated genes.

Minimal eating observation form: reliability and validity

OBJECTIVES

Eating difficulties are common for patients in hospitals (82% have one or more). Eating difficulties predict undernourishment, need for assistance when eating, length of hospital stay and level of care after hospital stay. Eating difficulties have through factor analysis (FA) been found to belong to three dimensions (ingestion, deglutition and energy). The present study investigates inter-observer reliability. Other questions at issue are if the findings from the previous FA can be confirmed, if adjustments need to be done and if the Minimal Eating Form (MEOF) can serve as an assessment model for identification of eating difficulties. Previously found associations between eating difficulties and outcomes as well as measures taken to improve oral intake were also investigated.

DESIGN

Inter-observer study and cross-sectional observational study.

SETTINGS

Hospitals and special accommodations (SAs).

PARTICIPANTS AND MEASUREMENTS

Inter-observer study: Observers made standardized assessments of eating, independently and at the same time, on a sample of 50 patients with stroke. Survey study: 2600 (88%) out of 2945 persons agreed to participate in a survey of eating and nutrition. All SAs within six municipalities and six hospitals were involved. Nursing students, clinical tutors and staff performed the assessments, supported by the researchers.

RESULTS

The average agreement between observers of eating difficulties was 89% (Kappa coefficient 0.70). In the survey study, the mean age of persons (n=1726) living in SAs was 85 years (SD 8) and 69% were women, while the corresponding figures for patients (n=874) in hospitals were 69 years (SD 18) and 53% women. Low Body Mass Index (BMI) was found in 27%, unintentional weight loss in 23% and need of eating assistance in 38% of the persons. Protein- and energy- (PE-) enriched food was given to 4%, adapted consistency of food to 23% and food supplements to 16% of the persons. The new FA confirmed the previous one and minor adjustments of the model were made. Having ingestion difficulties was the strongest predictor of need for eating assistance (OR 14.5). Deglutition difficulties strongly predicted serving of adapted consistency of food (OR 7.3). Poor energy levels and reduced appetite predicted weight loss (OR 6.0), BMI below limits (OR 2.5), supplements (OR 5.3) and PE-enriched food (OR 3.4).

CONCLUSIONS

The MEOF has satisfying validity and reliability. The earlier model of eating difficulties was confirmed (MEOF-I), and the model was slightly adjusted to a new model, MEOF-II. Providing eating assistance seems effective in preventing malnutrition (weight loss and BMI below limits), and is mainly provided to persons with ingestion difficulties. Difficulties with energy intake and appetite are not associated with eating assistance; indicating that those persons might need support of some other kind. This support can include providing PE-enriched food and supplements, but seems however insufficiently or inadequately delivered, as low energy and appetite problems are also associated with both weight loss and low BMI. Findings from other studies are confirmed.

Rain events and their effect on effluent quality studied at a full scale activated sludge treatment plant

The effect of rain events on effluent quality dynamics was studied at a full scale activated sludge wastewater treatment plant which has a process solution incorporating pre-denitrification in activated sludge with post-nitrification in trickling filters. The incoming wastewater flow varies significantly due to a combined sewer system. Changed flow conditions have an impact on the whole treatment process since the recirculation to the trickling filters is set by the hydraulic limitations of the secondary settlers. Apart from causing different hydraulic conditions in the plant, increased flow due to rain or snow-melting, changes the properties of the incoming wastewater which affects process performance and effluent quality, especially the particle removal efficiency. A comprehensive set of on-line and laboratory data were collected and analysed to assess the impact of rain events on the plant performance.

Short circuiting in a denitrifying activated sludge tank

The presence of a short circuit flow in a denitrifying activated sludge tank was identified and modelled. Tracer tests with pulse addition of lithium salt were used to investigate the hydraulics of the tank. The lithium concentration in the effluent was detected and residence time distribution (RTD) curves were generated. Hydraulic models based on completely stirred tank reactors (CSTRs) in series were generated from the RTD curves and the models were compared. The short circuit problem was successfully described using the Martin model, where the inflow is divided into two strands. Each strand was modelled as a number of CSTRs in series. At a normal flow the results of the model show that the tank has 12.8% dead volume, 85.8% main volume and 1.3% short circuiting volume. The inflow was divided into 91.9% entering the main volume and 8.1% entering the short circuiting volume. The mean velocity of the short circuiting stream was estimated to 0.4 m/s. At maximum flow the short circuiting stream was even larger and handled 24.3% of the flow. The short circuiting stream was identified in the upper part of the tank due to the position of the inlet and the outlet. The configuration of a tank including the use of baffles, the geometry of the inlet and mixer configuration should be considered carefully if short circuiting is to be avoided.

Cell cycle arrest of human gingival fibroblasts and periodontal ligament cells byActinobacillus actinomycetemcomitans: involvement of the cytolethal distending toxin

The cytolethal distending toxin (Cdt) is produced by several Gram-negative bacterial species and causes growth arrest and morphological alterations in mammalian cells. Actinobacillus actinomycetemcomitans, which is involved in the pathogenesis of localized aggressive periodontitis, also produces a Cdt that affects periodontal connective tissue cells. The aim of this study was to investigate in which phase of the cell cycle these cells are arrested and enlarged when challenged with A. actinomycetemcomitans, and to evaluate the involvement of its Cdt. Human gingival fibroblasts and periodontal ligament cells were challenged with A. actinomycetemcomitans extract, or with purified Cdt, and cell cycle analysis was performed by propidium iodide staining and flow cytometry. Cells exposed to an A. actinomycetemcomitans wild-type strain, or to purified Cdt, were arrested in both G1 and G2/M phases, and appeared enlarged compared to the corresponding controls. The cellular enlargement occurred in both G1 and G2/M arrested cells. In contrast, cells exposed to an A. actinomycetemcomitans cdt-knockout mutant strain showed cell cycle phase distribution and size similar to the controls. In conclusion, A. actinomycetemcomitans causes a combined G1 and G2/M growth arrest and enlargement in periodontal connective tissue cells, which is attributed to its Cdt.

Reducing the total discharge from a large WWTP by separate treatment of primary effluent overflow

At many large wastewater treatment plants (WWTPs) the increased hydraulic load, caused by combined sewer systems during storm events, results in primary effluent overflow when the capacity of further treatment is exceeded. Due to stringent effluent standards, regulating the total discharge from the WWTPs, the Rya WWTP in Göteborg and the Sjölunda WWTP in Malmö will have to reduce the impact of primary effluent overflow. Separate, high rate, precipitation processes operated only during high flow conditions have been investigated in pilot units at the two WWTPs. Precipitation in existing primary settlers operated at a surface loading of 3.75 m/h removed phosphorus to 0.35 mg/l. The Actiflo process was also shown to remove suspended solids and phosphorus well. BOD was reduced by 50-60%. With such processes the overall effluent concentrations from the plants can be reduced significantly. Key upgrading features are small footprints, short start up time and high efficiency.

Loss of cortical acetylcholine enhances amphetamine-induced locomotor activity

Cholinergic disturbances have been implicated in schizophrenia. In a recent study we found that intracerebroventricular (i.c.v.) delivery of the immunotoxin 192 IgG-saporin, that effectively destroys cholinergic projections from the basal forebrain to hippocampus and cortex cerebri, leads to a marked facilitation of amphetamine-induced locomotor activity in adult rats. The aim of the present experiments was to evaluate the contribution of the septohippocampal versus the basalocortical cholinergic projections for the amphetamine hyper-response seen previously in i.c.v. 192 IgG-saporin injected rats. Since i.c.v. delivery of 192 IgG-saporin also destroys a population of Purkinje neurons in cerebellum, this cell loss needs to be taken into consideration as well. Cortex cerebri and hippocampus were selectively cholinergically denervated by intraparenchymal injections of 192 IgG-saporin into nucleus basalis magnocellularis and the medial septum/diagonal band of Broca, respectively. Selective loss of Purkinje cells in cerebellum was achieved by i.c.v. delivery of OX7 saporin. Possible effects of these three lesions on spontaneous and amphetamine-induced locomotor activity were assessed in locomotor activity cages. We find that selective cholinergic denervation of cortex cerebri, but not denervation of hippocampus or damage to cerebellum can elicit dopaminergic hyper-reactivity similar to that seen in previous i.c.v. 192 IgG-saporin experiments. Our data are compatible with the hypothesis that disturbances of cholinergic neurotransmission in cortex cerebri may be causally involved in forms of schizophrenia.

Tensile properties of a bone cement containing non-ionic contrast media

The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.

Excess breast cancer risk and the role of parity, age at first childbirth and exposure to radiation in infancy

Exposure to ionizing radiation is a known risk factor for breast cancer and the fertility pattern is a recognized modifier of breast cancer risk. The aim of this study was to elucidate the interaction between these 2 factors. This study is based on a Swedish cohort of 17 202 women who had been irradiated for skin haemangiomas in infancy between 1920 and 1965. The mean age at treatment was 6 months and the median breast dose was 0.05 Gy (range 0-35.8 Gy). Follow-up information on vital status, parity, age at first childbirth and breast cancer incidence was retrieved through record linkage with national population registers for the period 1958-1995. Analyses of excess relative risk (ERR) models were performed using Poisson regression methods. In this cohort, the fertility pattern differed from that in the Swedish population, with significantly fewer childbirths overall and before 25 years of age but more childbirth after that age. There were 307 breast cancers in the cohort and the standardized incidence ratio (SIR) was 1.22 (95% CI 1.09-1.36). A linear dose-response model with stratification for fertility pattern and menopausal status resulted in the best fit of the data. ERR/Gy was 0.33 (95% CI 0.17-0.53). In absolute terms this means an excess of 2.1 and 5.4 cases per Gy per 10(4) breast-years in the age groups 40-49 and 50-59 years respectively. The fertility pattern influenced the breast cancer risk in this irradiated population in a similar way to that observed in other studies. SIR at dose = 0 was highest, 2.31, among postmenopausal nulliparous women (95% CI 1.48-3.40, n = 62). SIR at dose = 0 was lowest in pre- or postmenopausal women with a first childbirth before 25 years of age; 0.89 (0.71-1.09) and 0.88 (0.58-1.25) respectively. Thus, in addition to the dose-effect response in the cohort, part of the breast cancer excess could be explained by a different fertility pattern. The estimates of ERR/Gy for the various categories of age at first childbirth, number of children, menopausal status and ovarian dose were very similar, contradicting any interaction effects on the scale of relative risk.

Selective antibody-induced cholinergic cell and synapse loss produce sustained hippocampal and cortical hypometabolism with correlated cognitive deficits

The physiological interrelationships between cognitive impairments, neurotransmitter loss, amyloid processing and energy metabolism changes in AD, cholinergic dementia and Down's syndrome are largely unknown to date. This report contains novel studies into the association between cognitive function and cerebral metabolism after long-term selective CNS cholinergic neuronal and synaptic loss in a rodent model. We measured local cerebral rates of glucose utilization ((14)C-2-deoxyglucose) throughout the brains of awake rats 4.5 months after bilateral intraventricular injections of a cholinotoxic antibody directed against the low-affinity NGF receptor (p75 NGF) associated with cholinergic neurons (192 IgG-saporin). Permanent cholinergic synapse loss was demonstrated by [(3)H]-vesamicol in vitro autoradiography defining presynaptic vesicular acetylcholine (ACh) transport sites. While other metabolic studies have defined acute and transient glucose use changes after relatively nonspecific lesions of anatomical regions containing cholinergic neurons, our results show sustained reductions in glucose utilization in brain regions impacted by cholinergic synapse loss, including frontal cortical and hippocampal regions, relative to glucose use levels in control rats. In the same animals, impaired cognitive spatial performance in a Morris water maze was correlated with reduced glucose use rates in the cortex and hippocampus at this time point, which is consistent with increased postmortem cortical and hippocampal amyloid precursor protein (APP) levels (45, 46). These results are consistent with the view of cholinergic influence over metabolism, APP processing, and cognition in the cortex and hippocampus.

Radiation risk and mammographic screening of women from 40 to 49 years of age: effect on breast cancer rates and years of life

The aim of this study was to evaluate the carcinogenic risks associated with radiation in mass mammographic screening. Assessment was in terms of breast cancer mortality and years of life for a hypothetical cohort of 100 000 women. Data were obtained on incidence, mortality and life expectancy for the female population of Stockholm. With a screening interval of 18 months at ages 40-49 years, a total absorbed dose to the breast of 13 mGy per invited woman; and an annual breast cancer reduction of 25% per year 7 years from screening start, the net number of years gained was at least 2800. However, using the highest absorbed dose reported in routine mammographic screening in Sweden (approximately 3 mGy per view), and the highest reported radiation risk in the literature, a programme entailing annual screening with 2 views would require at least a 20% annual reduction in breast cancer mortality to give a net benefit in both the number of years of life gained and number of breast cancer deaths avoided. This observation supports the conclusion that exposures with low absorbed dose are essential when performing mass screening with mammography among young women.

Cognitive changes and modified processing of amyloid precursor protein in the cortical and hippocampal system after cholinergic synapse loss and muscarinic receptor activation

A number of in vitro studies have shown that activation of muscarinic receptors by cholinergic agonists stimulates the nonamyloidogenic, alpha-secretase-processing pathway of amyloid precursor protein (APP). To determine whether increased cholinergic neurotransmission can modify the APP processing in vivo, we administered a muscarinic receptor agonist (RS86) to normal or aged rats and rats with severe basal forebrain cholinergic deficits (induced by 192 IgG-saporin). The levels of the cell-associated APP in neocortex, hippocampus, and striatum, as well as the secreted form of APP (APPs) in cerebrospinal fluid, were examined by Western blots. Additionally, we investigated the association between the altered APP levels and behavioral deficits caused by cholinergic lesions. We found that treatment with muscarinic receptor agonist resulted in decreased APP levels in neocortex and hippocampus and increased levels of APPs in cerebrospinal fluid. Regulation of APP processing by the muscarinic agonist treatment occurred not only in normal rats, but also in aged and cholinergic denervated rats that model this aspect of Alzheimer's disease. Interestingly, we found that elevation of APP in neocortex correlated with the cognitive deficits in water-maze testing of rats with cholinergic dysfunction. These data indicate that increased cholinergic neurotransmission can enhance nonamyloidogenic APP processing in intact and lesioned rats and that APP may be involved in cognitive performance.

Breast cancer risk after radiotherapy in infancy: a pooled analysis of two Swedish cohorts of 17,202 infants

The incidence of breast cancer was studied in a cohort of 17,202 women irradiated for skin hemangioma in infancy at the Radiumhemmet, Stockholm, or the Sahlgrenska University Hospital, Gothenburg. A major part of the cohort had been treated with radium-226 applicators, and the mean absorbed dose to the breasts was 0.29 Gy (range <0.01-35.8 Gy). Two hundred forty-five breast cancers were diagnosed in the cohort during the period 1958-1993, and the standardized incidence ratio (SIR) was 1.20 (95% CI 1.06-1.36). Different dose-response models were tested, and a linear model gave the best fit. Neither age at exposure, breast dose rate, ovarian dose nor time since exposure had any statistically significant modifying effect, and breast dose was the only determinant of risk. The excess relative risk per gray (ERR/Gy) was 0.35 (95% CI 0.18-0.59), which is lower than in most other studies.

Mortality after long-term exposure to radioactive Thorotrast: a forty-year follow-up survey in Sweden

To evaluate temporal patterns of cause-specific mortality after long-term exposure to the alpha-particle-emitting contrast medium Thorotrast, we investigated a cohort consisting of 693 Swedish patients with neurological disorders who received Thorotrast during cerebral angiography, with follow-up ending in 1993. Standardized mortality ratios (SMRs) were calculated as the ratio of observed cases in the cohort to expected cases in the general population. Persons exposed to Thorotrast had significant excesses of all causes of death (SMR = 2.8; 95% CI 2.5-3.0), with similar increases noted for men and women. The largest risks were observed for deaths from hematological causes (SMR = 16.4; n = 8), cerebrovascular diseases (SMR = 10.1; n = 18), gastrointestinal disorders including liver cirrhosis (SMR = 5.2; n = 36), and tumors (SMR = 4.7; n = 187). There was a significant decrease in SMR with time since injection for cerebrovascular and circulatory diseases, indicative of the impact of underlying neurological disorders. In contrast, the SMR increased significantly with time for tumors and gastrointestinal diseases, suggestive of a detrimental effect of cumulative radiation dose. A significant dose-response relationship was found for all causes of death and malignant tumors among all age groups, and since SMR increased with time for the latter category, this is consistent with an effect of cumulative radiation exposure on cancer development. However, the findings should be treated with caution, since selection bias may have influenced some of the results.

Stereological estimates of nuclear volume in thin malignant melanomas

Stereological estimation of nuclear volume was performed in a case control study of 72 malignant melanomas, thickness < or = 0.8 mm and Clark's level II-III. However, stereological measurements could be performed in only 57 thin melanomas due to too sparse cellularity. Thus, 21 thin metastasizing melanomas were individually compared with 33 thin non-metastasizing melanomas after individual matching of cases with one or two randomly chosen controls for site of primary tumour, tumour thickness, level of invasion, tumour regression and follow-up. Conditional logistic regression analysis showed no significant differences in nuclear volume between metastasizing and non-metastasizing thin malignant melanomas.

Human duodenogastric reflux, retroperistalsis, and MMC

The aim of this study was to determine to what extent human migrating motor complex (MMC)-related secretory phenomena are influenced by a recently discovered period of duodenal retroperistalsis during late phase III. A constant-flow perfusion technique was used to measure gastric appearance of acid, bicarbonate, pepsin, bilirubin, IgA, and duodenally infused [14C]polyethylene glycol (PEG) 4000 in 12 healthy volunteers. Interdigestive gastroduodenal motility was recorded by digital manometry. During late antral phase II and III, the gastric lumen was acidified (P < 0.005 phase III vs. phase I) together with a marked increase in luminal pepsin output (3.1 +/- 1.2 during phase III vs. 0.25 +/- 0.08 kU/5 min in phase I, P < 0.01), followed by a realkalinization due to a simultaneous reduction of acid secretion and a duodenogastric reflux, aided by retrograde peristalsis, of bicarbonate and IgA but not of bilirubin, at the end of antral phase III (P < 0.05 phase III vs. phase I values). This physiological duodenoantral reflux phenomenon may play an important role in the chemical and immunological restitution of the antral mucosal barrier function after the exposure to high acid and pepsin concentrations during antral phase III activity.

Intracranial tumors after exposure to ionizing radiation during infancy: a pooled analysis of two Swedish cohorts of 28,008 infants with skin hemangioma

The risk of intracranial tumors after exposure to ionizing radiation during infancy has been studied in a pooled analysis of two Swedish hemangioma cohorts (n = 28,008). The mean absorbed intracranial dose was low (7 cGy, range 0-11.5 Gy). The cohorts were followed up in the Swedish Cancer Register for incident intracranial tumors during the period 1958-1993. Eighty-eight tumors were found in 86 individuals compared to 60.72 expected [standardized incidence ratio (SIR) 1.42, 95% confidence interval (CI) 1.13-1.75]. The SIR increased significantly in ascending dose categories (P = 0.02). Dose-response analyses were performed with Poisson regression methods. There was a significant effect of dose, and the dose-effect relationship was negatively modified by age at first treatment. This indicates a higher risk for those exposed earlier in life. A linear dose-response model modified by age at first treatment resulted in the best fit. The excess relative risk (ERR) was 2.7/Gy (95% CI 1.0-5.6). The ERR/Gy was 4.5 if the treatment was given before 5 months of age, 1.5 if it was given at 5-7 months and 0.4 if it was given later. The study thus strongly indicates that there exists a dose-response relationship between absorbed dose in the brain and the subsequent risk of developing an intracranial tumor and that the risk is higher among infants exposed at younger ages.

Induction of B cell responses in the stomach of Helicobacter pylori- infected subjects after oral cholera vaccination

We have evaluated the possibility of inducing antibody responses locally in the human stomach as a prerequisite for the development of a vaccine against Helicobacter pylori. Both H. pylori-infected and noninfected subjects were immunized with an oral B subunit whole cell (BS-WC) cholera vaccine, and total and vaccine-specific antibody-secreting cells (ASC) were determined by the enzyme-linked immunospot (ELISPOT) technique in cells isolated from the antrum and duodenum, respectively, before and after vaccination. Most of the subjects responded to the vaccination with high frequencies of vaccine-specific ASCs in the duodenum as well as high-serum antibody titers, and no significant differences were seen in the responses between H. pylori- infected and noninfected subjects. When studying the gastric mucosa, on the other hand, there were dramatic differences between the H. pylori-infected and the noninfected subjects. Thus, whereas none of the noninfected subjects responded to the immunization in antrum, most of the H. pylori-infected subjects had high frequencies of vaccine-specific ASCs in this location after vaccination. Furthermore, the H. pylori-infected subjects had strikingly higher (as a mean 80-fold) frequencies of total IgA-secreting cells in antrum than the noninfected subjects, whereas the frequencies of total IgA-secreting cells in the duodenum were comparable between the groups. In conclusion, these results demonstrate the possibility of inducing antibody responses locally in the gastric mucosa of H. pylori-infected individuals, a finding with obvious implications for the future development of a therapeutic vaccine against H. pylori.

Antibody-secreting cells in the stomachs of symptomatic and asymptomatic Helicobacter pylori-infected subjects

In this study we analyzed whether infection with Helicobacter pylori gives rise to specific B-cell responses against a number of putative virulence factors of H. pylori, e.g., urease, flagellin, and different bacterial surface antigens, locally in the gastric mucosa. This was studied in antrum and corpus biopsies collected from 11 H. pylori-infected patients with duodenal ulcers, 11 asymptomatic H. pylori carriers, and 13 noninfected, healthy controls. Mononuclear cells were isolated from the biopsies and assayed for frequencies of total and H. pylori-specific antibody-secreting cells (ASCs) by means of the enzyme-linked immunospot technique. The H. pylori-infected subjects had remarkably higher frequencies of total immunoglobulin A (IgA)- and IgM-secreting cells than the noninfected subjects, while the frequencies of IgG-secreting cells were virtually the same in the different groups. In addition, most of the infected subjects had IgA ASCs reacting with H. pylori membrane proteins, flagellin, and urease, while none of the noninfected subjects had any detectable H. pylori-reactive ASCs. Furthermore, half of the infected subjects also had ASCs reacting with a Helicobacter-specific 26-kDa protein, while only a few of them had ASCs reacting with neutrophil-activating protein, the neuraminyllactose-binding hemagglutinin HpaA, or lipopolysaccharides purified from different H. pylori strains. The frequencies of H. pylori-specific ASCs in the antrum and corpus were almost identical, and no differences in either antigen specificity or magnitude of the B-cell response in the stomach could be detected between the ulcer patients and the asymptomatic H. pylori carriers. This study demonstrates that H. pylori infection induces strong antibody responses in the human gastric mucosa, both in asymptomatic carriers and in duodenal ulcer patients. However, the outcome of infection could not be explained by differences in the local B-cell response to any of the antigens used in this study.

Specific antibodies in sera and gastric aspirates of symptomatic and asymptomatic Helicobacter pylori-infected subjects

In this study we have determined systemic and local antibody responses against different Helicobacter pylori antigens in H. pylori-infected and noninfected subjects. In addition, we studied whether differences in antibody responses between patients with duodenal ulcers and asymptomatic H. pylori carriers might explain the different outcomes of infection. Sera and in most instances gastric aspirates were collected from 19 duodenal ulcer patients, 15 asymptomatic H. pylori carriers, and 20 noninfected subjects and assayed for specific antibodies against different H. pylori antigens, i.e., whole membrane proteins (MP), lipopolysaccharides, flagellin, urease, the neuraminyllactose binding hemagglutinin HpaA, and a 26-kDa protein, by enzyme-linked immunosorbent assay. The H. pylori-infected subjects had significantly higher antibody titers against MP, flagellin, and urease in both sera and gastric aspirates compared with the noninfected subjects. Furthermore, the antibody titers against HpaA were significantly elevated in sera but not in gastric aspirates from the infected subjects. However, no differences in antibody titers against any of the tested antigens could be detected between the duodenal ulcer patients and the asymptomatic H. pylori carriers, either in sera or in gastric aspirates.

Outcome of treatment for ipsilateral breast tumor recurrence in early-stage breast cancer

INTRODUCTION

The aims of the study were to assess the outcome among patients with early breast cancer operated on with wide local excision who developed a subsequent ipsilateral breast tumor recurrence, and to identify risk factors for uncontrolled local disease. Uncontrolled local disease (ULD) was defined as the appearance of clinically manifest invasive adenocarcinoma in the remaining breast or on the ipsilateral chest wall which could not be eradicated with salvage treatment during the period of follow-up (2-18 years).

PATIENTS AND METHODS

Eighty-five patients in a cohort of 759 patients, treated for invasive Stage I-II breast cancer with breast-conserving surgery 1976-1985 in Stockholm, with a subsequent ipsilateral breast tumor recurrence (IBTR) were reviewed retrospectively. The majority of the patients were premenopausal (58%), node negative (72%), and had received postoperative radiotherapy (79%). Median follow-up time following breast-conserving surgery was 13 (9-19) years. Multivariate Cox's hazard regression was used in the statistical analysis to identify prognostic factors for ULD.

RESULTS

The majority (n = 61) of the IBTR's were located in the original tumor quadrant and showed the same histopathological features as the primary tumor. Salvage mastectomy (n = 65) or reexcision (n = 14) were performed in 79 (93%) of the patients. Twenty-one patients developed ULD. Five years following the diagnosis of IBTR the disease-free survival was 59%, the cumulative incidence for ULD was 24%, and for death in breast cancer 34%. In the cohort of 759 patients, patients who received radiotherapy following the primary breast-conserving surgery had 1% cumulative incidence of ULD following the diagnosis of IBTR compared to 4% among patients that received no postoperative radiotherapy. The cumulative incidence at 5 years of ULD following salvage mastectomy was 12% compared to 33% after salvage reexcision. Patients operated on with breast-conserving surgery with an original tumor size < 15 mm, who were treated with salvage mastectomy for IBTR, had in multivariate analysis the lowest relative risk for ULD. Adjuvant chemotherapy following IBTR treatment did not seem to improve local tumor control. Following the diagnosis of IBTR, 78% (n = 21) of the patients with ULD and/or regional recurrence (n = 27), died of a disseminated breast cancer in contrast to 10% (n = 6) among the remaining 58 patients.

CONCLUSION

Uncontrolled local disease is an important outcome measure following breast-conserving surgery. In this cohort, salvage mastectomy provided a superior local control rate compared to salvage reexcision. A higher although not statistically significant rate of ULD was also seen in patients who had not received postoperative radiotherapy as part of their primary treatment.

Local and systemic immune responses in humans against Helicobacter pylori antigens from homologous and heterologous strains

The capacity of Helicobacter pylori to induce strain specific immune responses was studied in adult Swedish volunteers. Sera and gastric aspirates from 11 H. pylori-infected subjects were tested for specific antibody levels against, respectively, lipopolysaccharides (LPS) and total membrane preparations (MPs) prepared from the study subjects' own strains, as well as with corresponding antigens from two reference H. pylori strains or heterologous strains collected from other subjects within the study. It was found that sera from five of the 11 subjects had significantly higher IgA antibody titres against LPS from the homologous strain than against LPS from either of the reference strains and in five cases sera reacted with higher IgG titres against the homologous LPS than with LPS preparations from the reference or heterologous patient strains. Analyses of specific titres against MPs revealed that six sera had higher IgA titres and four sera had higher IgG titres against MPs prepared from the subjects' own strains than against MPs from either of the two reference strains. Determination of specific antibodies in gastric aspirates revealed significantly higher IgA titres against LPS from the homologous H. pylori isolate than against LPS from the two reference strains in five cases, and six aspirates reacted in higher IgA titre with the homologous H. pylori MPs. Results from immunoblotting analyses of sera support induction of strain specific immune responses against H. pylori LPS. By means of specific monoclonal antibodies against H. pylori LPS, antigenic heterogeneity between the different LPS preparations tested was confirmed.

Lack of detectable major histocompatibility complex class II a beta-chain messenger ribonucleic acid in placentas of interferon-gamma- and 5-azacytidine-treated mice

Trophoblast cells do not normally express major histocompatibility complex (MHC) class II antigens during placental development in either mice or rats. We have previously observed that in vivo treatment of pregnant mice with interferon-gamma (IFN gamma) induces immunohistochemically detectable class II cell surface expression in many maternal cell types, but not on placental cells or other cells of extra-embryonic origin. Both IFN gamma- and 5-azacytidine-induced placental class II expression have been reported in mice by other scientists, however, which made it important to further clarify this issue. The present study was performed to analyze whether treatment of pregnant mice with recombinant IFN gamma or the drug 5-azacytidine in vivo can induce detectable MHC class II Ab mRNA expression. A strain of transgenic mice carrying a cytomegalovirus-regulated MHC class II Abq transgene, which was strongly expressed in the placenta, was used as a positive control in all in situ hybridizations and ribonuclease protection analyses. All mice were analyzed on gestation Days 12.5 and 17.5. Treatment of pregnant mice with IFN gamma did not induce detectable class II expression in the placental cells, whereas the maternal decidua showed expression both at the mRNA and protein level. Similarly, treatment with 5-azacytidine did not induce class II expression in the placenta, while a slight increase in mRNA expression was detected in the maternal decidual and uterine tissues. These results strengthen the opinion that MHC class II mRNA cannot normally be induced in murine placental cells after IFN gamma or 5-azacytidine treatments.

Incidence of primary malignancies other than breast cancer among women treated with radiation therapy for benign breast disease

This report presents data on the long-term risks of developing malignancies other than breast cancer after exposure to scattered doses of ionizing radiation. The estimates were based on a cohort of 3,090 women who were diagnosed clinically with benign breast disease between 1925 and 1961. A total of 1,216 women were treated with radiation therapy. The breasts received a mean absorbed dose of 5.84 Gy. Mean absorbed doses owing to scatter to 14 other organs were also determined. The lung received the highest mean scattered dose (0.75 Gy; range 0.004-8.98 Gy) and rectum the lowest (0.008 Gy; range 0-0.06 Gy). Median age at first exposure was 40 years. The follow-up lasted up to 61 years after treatment (mean follow-up 27 years). End-point data were obtained from population-based registers. With internal reference the relative risk for non-breast solid tumors was 1.2 (95% confidence interval 1.0-1.5). However, this excess was not apparent when comparison with the general population was made (standardized incidence ratio = 0.95; 95% confidence interval 0.84-1.07). Among individual sites no significantly increased risks were observed. For stomach cancer there was a linear increase with dose (ERR/Gy = 1.3; two-sided P = 0.05). No increased risk was observed for leukemias. In two earlier reports, breast cancer incidence has been shown to be significantly increased in this cohort of irradiated women. Our results suggest that the scattered doses from the breast irradiation may have increased the risk of cancers of other sites, but the small number of cases in different locations precludes strong interpretations.

Relationship between interdigestive motility and secretion of immunoglobulin A in human proximal small intestine

In 17 healthy volunteers, we studied the dynamics of secretory immunoglobulin A (SIgA) release in the proximal small intestine (distal duodenum and proximal jejunum), using a modified triple-lumen perfusion technique. Secretory data were related to the current phase of the migrating motor complex (MMC), as recorded by manometry. In both segments, luminal SIgA output changed cyclically, with peak outputs occurring at the end of the MMC cycle (late phase II). These MMC-related changes were due to two factors: cyclic inflow of SIgA from more proximal sites, and a cyclic release of SIgA from the test segment that correlated in time with an increase in epithelial fluid secretion. Cyclic intestinal SIgA release may thus be another secretory component of the MMC. The data are compatible with the hypothesis that motility and SIgA release are linked by motility-activated chloride secretion from the intestinal crypts.

Breast conserving surgery for invasive breast cancer: risk factors for ipsilateral breast tumor recurrences

To identify risk factors associated with an increased risk for ipsilateral breast tumor recurrence following breast-conserving surgery, a cohort of 759 women with T1-T2 tumors were studied. The majority of the patients (88%) had received postoperative radiation therapy to the breast. Median follow-up time was 10 (range: 6-17) years. There was a 1-1.5% yearly increase in ipsilateral breast tumor recurrences. For women < 50 ys the cumulative recurrence rate at 10 years was 18% and for women > or = 50 ys, 9%. Node positive women had a cumulative breast recurrence rate of 25% versus 10% for node negative women. Ten years postoperatively, irradiated patients had a cumulative recurrence rate of 11% versus 26% when no irradiation was given. The beneficial effect of radiotherapy was substantial during the first four postoperative years. The relative risk for an ipsilateral breast tumor recurrence during this period was 4.5 times higher than for non-irradiated patients. However, the protective effect of radiotherapy decreased with time. After ten years the relative risk of ipsilateral breast tumor recurrence was the same among irradiated and non-irradiated patients although the number of events during this period was low. Univariate analysis showed that seven factors were significantly associated with an increased risk of ipsilateral breast tumor recurrence, namely age < 50 ys, increasing tumor size, uncertain microscopic margins, axillary lymph node metastases, no postoperative tamoxifen treatment, premenopausal status, and no postoperative radiotherapy. Three factors remained independently significant after multivariate analysis: age < 50 ys, no postoperative radiation therapy, and positive lymph nodes. In conclusion, radiotherapy reduced the breast recurrence rate, but the effect decreased with time. Node-negative women > or = 50 were a low risk-group for ipsilateral breast tumor recurrence, with a cumulative risk at 10 years of 9% without radiation therapy and 5% with breast irradiation.

Thyroid nodularity after diagnostic administration of iodine-131

In contrast to external X and gamma radiation, radiation from internally deposited 131I has not been clearly shown to cause thyroid tumors or nodules. Given the wide use of 131I in medicine and concern about health risks associated with the release of radioiodines from nuclear reactors, more information is needed. The purpose of this study was to evaluate the risk of thyroid nodularity among women previously exposed to radioiodine (131I) for diagnostic reasons. A clinical examination survey, including thyroid palpation, was conducted for a sample of women drawn from a cohort of patients exposed to 131I and a comparison group of women attending a mammography screening clinic. The study was conducted during 1991-1993 at Radiumhemmet, Karolinska Hospital, Stockholm, Sweden. A total of 1,005 women referred for a thyroid scintigraph or tracer test during the period 1952-1977 were included in the study. For comparison, 248 nonexposed women attending a mammography screening clinic were also enrolled. The primary outcome measure was the presence or absence of palpable thyroid nodules at the time of the clinical examination. Odds ratios were used as estimates of relative risk (RR). The mean dose to the thyroid from 131I was 0.54 Gy, and the average age at 131I administration was 26 years. The prevalence of thyroid nodularity was 10.6% among women who had been exposed to 131I and 11.7% among the nonexposed women [RR = 0.9; 95% confidence interval (CI) 0.6-1.4]. When analysis was restricted to women exposed to 131I, prevalence was associated positively with thyroid dose (excess RR = 0.9 per Gy; 95% CI 0.2-1.9). However, the excess RR was similar for women exposed before age 20 years and those exposed after age 20, which is contrary to findings for populations exposed to external radiation. While results demonstrated a positive association between diagnostic administration of 131I and the subsequent occurrence of thyroid nodules, it is unclear whether the association is causal, as the possibility of confounding by indication for 131I administration cannot be ruled out. No tumors that were subsequently diagnosed as cancer were found during the thyroid examinations, which supports the view that exposure to 131I administered for diagnostic reasons during adulthood rarely causes thyroid cancer.

Maternal antibodies protect immunoglobulin deficient neonatal mice from mouse hepatitis virus (MHV)-associated wasting syndrome

PROBLEM

Neonatal mice nursed by dams lacking immunoglobulins (Igs) may often suffer from lethal runting if raised under conventional conditions. The present study was performed in order to clarify a) the cause of the wasting syndrome and b) the protective role of antigen-specific milk antibodies.

METHOD

Ig-deficient mouse embryos in a conventional environment were embryo-transferred to specified pathogen free (SPF) dams. Neonatal growth, mortality, and health status of mice from both environments was recorded. Suspected presence of mouse hepatitis virus (MHV) was tested by RT-PCR. Protective effects on neonatal mortality of milk containing different titers of anti-MHV antibodies were investigated in cross-fostering experiments.

RESULTS

The SPF colony of Ig-deficient mice exhibited no breeding problems, whereas Ig-deficient neonates in the conventional environment suffered from lethal wasting syndrome. Serological screening of the mice kept in the two environments revealed that mice in the conventional room had high titers of antibodies against mouse hepatitis virus. Presence of MHV in runting neonates was confirmed by pathological examinations and RT-nested-PCR using MHV genome specific primers. Milk containing high titers of anti-MHV antibodies, when provided for 8 days or more, completely prevented Ig-deficient neonates from developing wasting syndrome in the conventional environment.

CONCLUSION

These findings show that the neonatal wasting syndrome is associated with the presence of MHV and that neonates are efficiently protected by MHV-specific antibodies in the milk.

Breast cancer after radiotherapy for skin hemangioma in infancy

Between 1920 and 1959, 9675 women were irradiated in infancy for skin hemangioma at Radiumhemmet, Stockholm. They were exposed to low to moderate doses of ionizing radiation. The mean age at first exposure was 6 months and the mean absorbed dose to the breast anlage was 0.39 Gy (range <0.01-35.8 Gy). The breast cancer incidence was analyzed by record linkage with the Swedish Cancer Register for the period 1958-1986. Seventy-five breast cancers were found [standardized incidence ratio = 1.24; 95% confidence interval (CI) 0.98-1.54] after a mean absorbed dose of 1.5 Gy in the breasts with cancer. The analyses showed a significant dose-response relationship with a linear model estimate for the excess relative risk (ERR) of 0.38 at 1 Gy 95% CI 0.09-0.85). This relationship was not modified significantly by age at exposure or by dose to the ovaries. The ERR increased significantly with time after exposure and for > or = 50 years after exposure the ERR at 1 Gy was 2.25 (95% CI 0.59-5.62). The fitted excess absolute risk (EAR) was 22.9 per 10(4) breast-year gray. The breast absorbed dose and time after exposure were important risk determinants for breast cancer excess risk. Forty to 50 years of follow-up was necessary for the excess risk to be expressed. The study confirms previous findings that the breast anlage of female infants is sensitive to ionizing radiation.

Thyroid cancer after diagnostic administration of iodine-131

To provide quantitative data on the risk of thyroid cancer after exposure to 131I, 34,104 patients administered 131I for diagnostic purposes were followed for up to 40 years. The mean thyroid dose was estimated as 1.1 Gy, and 67 thyroid cancers occurred in contrast to 49.7 expected (standardized incidence ratio = 1.35; 95% confidence interval 1.05-1.71). Excess cancers were apparent only among patients referred because of a suspected thyroid tumor, and no increased risk was seen among those referred for other reasons. Further, risk was not related to radiation dose to the thyroid gland, time since exposure or age at exposure. The slight excess of thyroid cancer thus appeared to be due to the underlying thyroid condition and not radiation exposure. Among those under age 20 years when 131I was administered, a small excess risk (3 cancers compared to 1.8 expected) was about 2-10 times lower than that predicted from data for the A-bomb survivors. These data suggest that protraction of dose may result in a lower risk than an acute X-ray exposure of the same total dose.

Adequate locoregional treatment for early breast cancer may prevent secondary dissemination

PURPOSE

To analyze different events that determine event-free survival (EFS) in a randomized trial on adjuvant radiotherapy in early breast cancer patients with more than 15 years of follow-up evaluation.

PATIENTS AND METHODS

The trial included 960 patients with a unilateral, operable breast cancer. Surgery consisted of a modified radical mastectomy. The trial compared three arms, as follows: preoperative radiotherapy, postoperative radiotherapy, and no adjuvant treatment. Events were analyzed by a competing-risk approach. A proportional hazards multiple regression model was used to analyze the effects of radiotherapy on the risk of distant metastasis. Similar analyses were performed separately for node-negative [N(-)] and node-positive [N(+)] patients in the two groups that did not include preoperative radiotherapy.

RESULTS

Radiotherapy produced a fivefold decrease of the risk of local recurrence (P < .0001). In N(+) patients, postoperative radiotherapy decreased the risk of distant dissemination (relative risk, 0.63). When local recurrence was introduced in the model as a time-dependent covariate, this factor was predictive of distant dissemination (P < .0001) and nullified the effect of postoperative radiotherapy. This finding suggests that the decrease of distant metastases was related to the prevention of local recurrence. A similar effect was found in models that used overall survival as an end point.

CONCLUSION

This study shows that postmastectomy radiotherapy in N(+) breast cancer patients may decrease the distant metastasis rate by preventing local recurrences and thus avoiding secondary dissemination.

Dose- and time-response for breast cancer risk after radiation therapy for benign breast disease

Exposure of the breast to ionising radiation increases the risk of breast cancer, especially among young women. However, some issues remain controversial, for instance the shape of the dose-response curve and the expression of time-related excess. The main purpose of this report was to examine the dose-response curves for radiation-induced breast cancer formulated according to radiobiological target theories. Another purpose was to analyse the time-related excess of breast cancer risk after exposure when dose and age at first exposure were held constant. Breast cancer incidence was analysed in a cohort of 3090 women diagnosed with benign breast disease during 1925-61 (median age 37 years). Of these, 1216 were treated with radiation therapy. The dose range was 0-50 Gy (mean 5.8 Gy). The incidence rate as function of dose was analysed using a linear-quadratic Poisson regression model. Cell-killing effects and other modifying effects were incorporated through additional log-linear terms. Additive and multiplicative models were compared in estimating the time-related excess. The analysis, which was based on 278 breast cancer cases, showed a linear dose-response relationship at low to medium dose levels with a cell-killing effect of 5% Gy-1 (95% confidence interval 2-9%). For a given absorbed dose and age at first exposure the time-related excess was proportional to the background rates with a suggestion that the excess remains throughout life.

Non-Hodgkin's lymphoma and skin malignancies--shared etiology?

The Stockholm-Gotland Cancer Register was used to evaluate the clinical observation that patients with non-Hodgkin's lymphoma (NHL) had an increased risk of malignant melanoma or squamous-cell carcinoma of the skin (SCCS) and vice versa. During 1958-1992, NHL was diagnosed in a total of 6,176 patients. Of these patients, 504 developed a second primary cancer of any type except NHL, compared to 301.9 expected, giving a standardized incidence ratio (SIR) of 1.7 [95% confidence interval (CI) 1.5-1.8]. The risk of SCCS and malignant melanoma in patients with NHL was 4.8 (95% CI 3.6-6.2; n = 54) and 1.7 (95% CI 0.8-3.1; n = 10), respectively. The hazard risk for a second malignancy was relatively constant over time, whereas the skin malignancies revealed the highest risks 3-10 years after initial diagnosis. Similarly, the risk of a secondary NHL was studied in patients with malignant melanoma and SCCS during the same period and found to be 1.3 (95% CI 0.8-2.1; n = 17) and 1.8 (95% CI 1.2-2.5; n = 34), respectively. The highest risk for NHL following malignant melanoma was seen 3-10 years after first diagnosis, while the highest risk following SCCS was observed 0-2 years after initial diagnosis. One of several possible explanations or the development of NHL and a skin malignancy in the same patient is an immunological defect caused by sun exposure.

Gastric output of IgA in man: relation to migrating motility complexes and sham feeding

BACKGROUND/AIMS

The immunologic reactivity of the gastric mucosa is poorly understood. The origin and dynamics of immunoglobulin A (IgA) occurring in the gastric lumen were investigated in healthy, Helicobacter pylori-negative volunteers.

METHODS

Gastroduodenal manometric motility recordings were combined with gastric luminal perfusion, enabling calculation of gastric acid output and analysis of the total IgA output.

RESULTS

Acid output and total IgA correlated with the migrating motility complexes (MMC). The gastric IgA release showed maximal values in association with gastric motility phase III (maximal motor activity) and lowest values during phases I and II (none or irregular motor activity). The IgA output correlated with neither swallowed saliva (as indicated by amylase in the gastric perfusate) nor duodenogastric reflux (as indicated by gastric occurrence of bilirubin and/or duodenally infused PEG4000). Stimulation of gastric acid secretion by sham feeding during phase II-like motor activity (n = 6) induced a rapid and transient doubling of IgA output. There was no significant correlation between gastric acid secretion and gastric IgA release.

CONCLUSION

Substantial amounts of IgA are released into the human stomach, most likely originating from the gastric mucosa. The up-regulation of IgA release in association with the activity front of the MMC and anticipatory to food intake suggests a neuroendocrine control of gastric mucosal immune responses.

Adolescent depression: effects of mutuality in the mother-adolescent dyad and locus of control

A group of 213 adolescents and their mothers participated in a study of the combined relationship between gender, locus of control, and perceived mutuality in the mother/adolescent dyad and self-rated adolescent depression. High mutuality and internal locus of control were significantly related to low levels of depression for both female and male adolescents. The study findings are considered in the context of current theoretical work on female relational psychology.