Thickness of peat influences the leaching of substances and greenhouse gas emissions from a cultivated organic soil

The off-site effects of agricultural organic soils include the leaching of N, P, and organic carbon (OC) to watercourses and CO₂, CH₄, and N₂O emissions into the atmosphere. The aim of this study was to quantify how the thickness of organic layers affects these loads. A 19.56-ha experimental field drained by subsurface pipes was established in Ruukki, northwestern Finland. Three plots had a 60-80 cm-thick sedge peat layer and three others had a thickness of 20 cm or less. The drainage pipes lie in mineral soil that, in this field, contains sulfidic material. This study documents the experimental settings and reports on the leaching of substances in the first two years, as well as CO₂, CH₄ and N₂O emissions during eight weeks in one summer. Total N (TN) and OC loads were higher from the thicker peat plots. The mean TN loads during a hydrological year were 15.4 and 9.2 kg ha^-1 from the thicker and thinner peat plots, respectively, with organic N representing 36% of TN load. Total P (TP) load averaged 0.27 kg ha^-1 yr^-1. Dissolved P load represented 63 and 36% of TP in the thicker peat area and only 23 and 13% in the thinner peat area, and was thus increased upon peat thickness. These N and P loads through the subsurface drainage system represented roughly 83% of TN and 64% of TP loads from this field. There were no clear differences in greenhouse gas emissions among the plots during the eight-week monitoring period. Slowly oxidizing sulfide in the subsoil resulted in annual leaching of 147 kg S ha^-1, almost ten times that of non-sulfidic soils. Our first results emphasize the effect of the peat thickness on the leaching of substances and warn about considering all organic soils as a single group in environmental assessments.

Nitrogen stocks and flows in an acid sulfate soil

Besides causing acidification, acid sulfate (AS) soils contain large nitrogen (N) stocks and are a potential source of N loading to waters and nitrous oxide (N₂O) emissions. We quantified the stocks and flows of N, including crop yields, N leaching, and N₂O emissions, in a cultivated AS soil in western Finland. We also investigated whether controlled drainage (CD) and sub-irrigation (CDI) to keep the sulfidic horizons inundated can alleviate N losses. Total N stock at 0-100 cm (19.5 Mg ha^-1) was smaller than at 100-200 cm (26.6 Mg ha^-1), and the mineral N stock was largest below 170 cm. Annual N leaching (31-91 kg N ha^-1) plus N in harvested grain (74-122 kg N ha^-1) was 148% (range 118-189%) of N applied in fertilizers (90-125 kg N ha^-1) in 2011-2017, suggesting substantial N supply from soil reserves. Annual emissions of N₂O measured during 2 years were 8-28 kg N ha^-1. The most probable reasons for high N₂O emission rates in AS soils are concomitant large mineral N pools with fluctuating redox conditions and low pH in the oxidized subsoil, all favoring formation of N₂O in nitrification and denitrification. Although the groundwater level was higher in CD and CDI than in conventional drainage, N load and crop offtake did not differ between the drainage methods, but there were differences in emissions. Nitrogen flows to the atmosphere and drainage water were clearly larger than those in non-AS mineral soils indicating that AS soils are potential hotspots of environmental impacts.

Hypothalamic γ-melanocyte stimulating hormone gene delivery reduces fat mass in male mice

γ-Melanocyte stimulating hormone (γ-MSH) is an endogenous agonist of the melanocortin 3-receptor (MC3R). Genetic disruption of MC3Rs increases adiposity and blunts responses to fasting, suggesting that increased MC3R signaling could be physiologically beneficial in the long term. Interestingly, several studies have concluded that activation of MC3Rs is orexigenic in the short term. Therefore, we aimed to examine the short- and long-term effects of γ-MSH in the hypothalamic arcuate nucleus (ARC) on energy homeostasis and hypothesized that the effect of MC3R agonism is dependent on the state of energy balance and nutrition. Lentiviral gene delivery was used to induce a continuous expression of γ-Msh only in the ARC of male C57Bl/6N mice. Parameters of body energy homeostasis were monitored as food was changed from chow (6 weeks) to Western diet (13 weeks) and back to chow (7 weeks). The γ-MSH treatment decreased the fat mass to lean mass ratio on chow, but the effect was attenuated on Western diet. After the switch back to chow, an enhanced loss in weight (−15% vs −6%) and fat mass (−37% vs −12%) and reduced cumulative food intake were observed in γ-MSH-treated animals. Fasting-induced feeding was increased on chow diet only; however, voluntary running wheel activity on Western diet was increased. The γ-MSH treatment also modulated the expression of key neuropeptides in the ARC favoring weight loss. We have shown that a chronic treatment intended to target ARC MC3Rs modulates energy balance in nutritional state-dependent manner. Enhancement of diet-induced weight loss could be beneficial in treatment of obesity.

Factors affecting the sorption of cesium in a nutrient-poor boreal bog

(135)Cs is among the most important radionuclides in the long-term safety assessments of spent nuclear fuel, due to its long half-life of 2.3 My and large inventory in spent nuclear fuel. Batch sorption experiments were conducted to evaluate the sorption behavior of radiocesium ((134)Cs) in the surface moss, peat, gyttja, and clay layers of 7-m-deep profiles taken from a nutrient-poor boreal bog. The batch distribution coefficient (Kd) values of radiocesium increased as a function of sampling depth. The highest Kd values, with a geometric mean of 3200 L/kg dry weight (DW), were observed in the bottom clay layer and the lowest in the 0.5-1.0 m peat layer (50 L/kg DW). The maximum sorption in all studied layers was observed at a pH between 7 and 9.5. The in situ Kd values of (133)Cs in surface Sphagnum moss, peat and gyttja samples were one order of magnitude higher than the Kd values obtained using the batch method. The highest in situ Kd values (9040 L/kg DW) were recorded for the surface moss layer. The sterilization of fresh surface moss, peat, gyttja and clay samples decreased the sorption of radiocesium by 38%, although the difference was not statistically significant. However, bacteria belonging to the genera Pseudomonas, Paenibacillus, Rhodococcus and Burkholderia isolated from the bog were found to remove radiocesium from the solution under laboratory conditions. The highest biosorption was observed for Paenibacillus sp. V0-1-LW and Pseudomonas sp. PS-0-L isolates. When isolated bacteria were added to sterilized bog samples, the removal of radiocesium from the solution increased by an average of 50% compared to the removal recorded for pure sterilized peat. Our results demonstrate that the sorption of radiocesium in the bog environment is dependent on pH and the type of the bog layer and that common environmental bacteria prevailing in the bog can remove cesium from the solution phase.

Iron and iron-based alloys for temporary cardiovascular applications

In the last decade, biodegradable metals have emerged as a topic of interest for particular biomedical applications which require high strength to bulk ratio, including for cardiovascular stents. The advantages of biodegradable materials are related to the reduction of long term risks associated with the presence of permanent metal implants, e.g. chronic inflammation and in-stent restenosis. From a structural point of view, the analysis of the literature reveals that iron-based alloys used as temporary biodegradable stents have several advantages over Mg-based alloys in terms of ductility and strength. Efforts on the modification and tunability of iron-based alloys design and compositions have been mainly focused on controlling the degradation rate while retaining the mechanical integrity within a reasonable period. The early pre-clinical results of many iron-based alloys seem promising for future implants developments. This review discusses the available literature focusing mainly on: (i) Fe and Fe-based alloys design and fabrication techniques; (ii) in vitro and in vivo performance; (iii) cytotoxicity and cell viability tests.

Isolation and characterization of Yersinia-specific bacteriophages from pig stools in Finland

AIMS

Bacteriophages infect bacteria, and they are present everywhere in the world including the intestinal tracts of animals. Yersiniosis is a common foodborne infection caused by Yersinia enterocolitica and Yersinia pseudotuberculosis. As these bacteria are frequently isolated from pigs, we wanted to know whether Yersinia-specific bacteriophages are also present in the pig stools and, if so, whether there is a positive or negative association between the prevalence of the Yersinia phages and the pathogenic Yersinia in the stool samples.

METHODS AND RESULTS

Altogether 793 pig stool samples collected between November 2010 and March 2012 from 14 Finnish pig farms were screened for the presence of bacteriophages able to infect Y. enterocolitica serotype O:3, O:5,27 or O:9 strains, or Y. pseudotuberculosis serotype O:1a, O:1b or O:3 strains. Yersinia phages were isolated from 90 samples from eight farms. Yersinia enterocolitica O:3 was infected by 59 phages, 28 phages infected serotypes O:3 and O:5,27, and eight phages infected serotypes O:3, O:5,27 and O:9, and Y. pseudotuberculosis O:1a by eight phages. Many phages originating from pigs in the same farm were identical based on their restriction enzyme digestion patterns; 20 clearly different phages were selected for further characterization. Host ranges of these phages were tested with 94 Yersinia strains. Six of the phages infected eight strains, 13 phages infected three strains, and one phage infected only one strain, indicating that the phages had a relatively narrow host range.

CONCLUSIONS

There was a clear association between the presence of the host bacteria and specific phages in the stools.

SIGNIFICANCE AND IMPACT OF THE STUDY

The isolated bacteriophages may have potential as biocontrol agents for yersiniosis in both humans and pigs in future, and as alternatives or in addition to antibiotics. To our knowledge, this is the first reported isolation of Yersinia-specific phages from pig stool samples.

A multi-scale comparison of dissolved Al, Fe and S in a boreal acid sulphate soil

Acid sulphate (AS) soils are most prevalent in the tropics, but the acidic discharge from cultivated AS soils also threatens water bodies under boreal conditions. Feasible options to reduce the acid load are needed. In this study, the groundwater of an AS field was monitored for 3.5 years, and the efficiency of waterlogging in mitigating the environmental risks caused by acidic discharge was investigated in a 2.5-year experiment with 10 monolithic lysimeters taken from the same field. In order to unravel the transferability of the results from lysimeters to the field scale, the Al, Fe and S concentrations in discharge water from the lysimeters were compared with those in the groundwater of the AS field (pedon and field scale), and in pore water (pedon and horizon scale). In the waterlogged bare lysimeters (HWB), the Al, Fe and S concentrations in discharge waters were broadly similar to those measured in the groundwater and followed the changes in the pore water. In the waterlogged cropped (reed canary grass, Phalaris arundinacea) lysimeters (HWC), in contrast, the discharge waters were markedly higher in Fe and lower in Al than the groundwater in the field. This outcome was attributable to the reduction of Fe(3+) to the more soluble Fe(2+) and the reduction-induced increase in pH, which enhanced the formation of Al(3+) hydroxy species. Lowering of the water table (LWC) caused soil ripening, which resulted in increased saturated hydraulic conductivity and porosity and enhanced the oxidation of sulphidic materials and acid formation. The responses of Al, Fe and S in drainage waters from HWC and LWC lysimeters resembled previous findings in AS soils. Based on this and the similarity between dissolved element concentrations in the discharge water of HWB lysimeters and groundwater in the field, we conclude that our monolithic lysimeters yielded realistic results concerning the efficiency of various methods in mitigating environmental risks related to cultivated AS soils.

Response of pore water Al, Fe and S concentrations to waterlogging in a boreal acid sulphate soil

Environmental hazards caused by acid sulphate (AS) soils are of worldwide concern. Among various mitigation measures, waterlogging has mainly been studied in subtropical and tropical conditions. To assess the environmental relevance of waterlogging as a mitigation option in boreal AS soils, we arranged a 2.5-year experiment with monolithic lysimeters to monitor changes in the soil redox potential, pH and the concentrations of aluminium (Al), iron (Fe) and sulphur (S) in pore water in response to low and high groundwater levels in four AS soil horizons. The monoliths consisted of acidic oxidized B horizons and a reduced C horizon containing sulphidic material. Eight lysimeters were cropped (reed canary grass, Phalaris arundinacea) and two were bare without a crop. Waterlogging was conducive to reduction reactions causing a slight rise in pH, a substantial increase in Fe (Fepw) and a decrease in Al (Alpw) in the pore water. The increase in Fepw was decisively higher in the cropped waterlogged lysimeters than in the bare ones, which was attributable to the microbiologically catalysed reductive dissolution of poorly ordered iron oxides and secondary minerals. In contrast to warmer climates, Fepw concentrations remained high throughout the experiment, indicating that the reduction was poised in the iron range, while sulphate was not reduced to sulphide. Therefore, the precipitation of iron sulphide was negligible in the environment with a low pH and abundant with poorly ordered Fe oxides. Increased Fe in pore water counteracts the positive effects of waterlogging, when water is flushed from fields to watercourses, where re-oxidation of Fe causes acidity and oxygen depletion. However, waterlogging prevented further oxidation of sulphidic materials and decreased Alpw to one-tenth of the initial concentrations, and even to one-hundredth of the levels in the low water table lysimeters.

Introduction of infected animals to herds is an important route for the spread of Yersinia enterocolitica infection between pig farms

Altogether, 369 pathogenic Yersinia enterocolitica isolates from 1,118 fecal samples collected from 22 pig farms of different production types were characterized by biotyping, serotyping, and genotyping using multiple-locus variable-number tandem repeats analysis. We investigated the distribution of the different genotypes at the farm level and their association with different farm conditions. Pigs were found to carry and transmit Y. enterocolitica between farms, because the same genotypes were found on farms that had previously transported the pigs between them. The purchase of new animals for the farms associated significantly with the number of different multiple-locus variable-number tandem repeats analysis types of Y. enterocolitica found within a farm. Some genotypes seemed to persist on farms for years. The results of this study show that pigs purchased from infected herds transmit Y. enterocolitica infection between farms. Certain pig farms may act as long-term sources of infection.

The microbial communities and potential greenhouse gas production in boreal acid sulphate, non-acid sulphate, and reedy sulphidic soils

Acid sulphate (AS) soils along the Baltic coasts contain significant amounts of organic carbon and nitrogen in their subsoils. The abundance, composition, and activity of microbial communities throughout the AS soil profile were analysed. The data from a drained AS soil were compared with those from a drained non-AS soil and a pristine wetland soil from the same region. Moreover, the potential production of methane, carbon dioxide, and nitrous oxide from the soils was determined under laboratory conditions. Direct microscopic counting, glucose-induced respiration (GIR), whole cell hybridisation, and extended phospholipid fatty acid (PLFA) analysis confirmed the presence of abundant microbial communities in the topsoil and also in the deepest Cg2 horizon of the AS soil. The patterns of microbial counts, biomass and activity in the profile of the AS soil and partly also in the non-AS soil therefore differed from the general tendency of gradual decreases in soil profiles. High respiration in the deepest Cg2 horizon of the AS soil (5.66 μg Cg(-1)h(-1), as compared to 2.71 μg Cg(-1)h(-1) in a top Ap horizon) is unusual but reasonable given the large amount of organic carbon in this horizon. Nitrous oxide production peaked in the BCgc horizon of the AS and in the BC horizon of the non-AS soil, but the peak value was ten-fold higher in the AS soil than in the non-AS soil (82.3 vs. 8.6 ng Ng(-1)d(-1)). The data suggest that boreal AS soils on the Baltic coast contain high microbial abundance and activity. This, together with the abundant carbon and total and mineral nitrogen in the deep layers of AS soils, may result in substantial gas production. Consequently, high GHG emissions could occur, for example, when the generally high water table is lowered because of arable farming.

Lentivirus-mediated α-melanocyte-stimulating hormone overexpression in the hypothalamus decreases diet induced obesity in mice

Melanocyte stimulating hormone (MSH) derived from the pro-hormone pro-opiomelanocortin (POMC) has potent effects on metabolism and feeding that lead to reduced body weight in the long-term. To determine the individual roles of POMC derived peptides and their sites of action, we created a method for the delivery of single MSH peptides using lentiviral vectors and studied the long-term anti-obesity effects of hypothalamic α-MSH overexpression in mice. An α-MSH lentivirus (LVi-α-MSH-EGFP) vector carrying the N'-terminal part of POMC and the α-MSH sequence was generated and shown to produce bioactive peptide in an in vitro melanin synthesis assay. Stereotaxis was used to deliver the LVi-α-MSH-EGFP or control LVi-EGFP vector to the arcuate nucleus (ARC) of the hypothalamus of male C57Bl/6N mice fed on a high-fat diet. The effects of 6-week-treatment on body weight, food intake, glucose tolerance and organ weights were determined. Additionally, a 14-day pairfeeding study was conducted to assess whether the weight decreasing effect of the LVi-α-MSH-EGFP treatment is dependent on decreased food intake. The 6-week LVi-α-MSH-EGFP treatment reduced weight gain (8.4 ± 0.4 g versus 12.3 ± 0.6 g; P < 0.05), which was statistically significant starting from 1 week after the injections. The weight of mesenteric fat was decreased and glucose tolerance was improved compared to LVi-EGFP treated mice. Food intake was decreased during the first week in the LVi-α-MSH-EGFP treated mice but subsequently increased to the level of LVi-EGFP treated mice. The LVi-EGFP injected control mice gained more weight even when pairfed to the level of food intake by LVi-α-MSH-EGFP treated mice. We demonstrate that gene transfer of α-MSH, a single peptide product of POMC, into the ARC of the hypothalamus, reduces obesity and improves glucose tolerance, and that factors other than decreased food intake also influence the weight decreasing effects of α-MSH overexpression in the ARC. Furthermore, viral MSH vectors delivered stereotaxically provide a novel tool for further exploration of chronic site-specific effects of POMC peptides.

Spectroscopy in the analysis of bacterial and eukaryotic cell footprints on implant surfaces

We tested the suitability of two spectroscopic methods, x-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), in the recognition of bacterial and eukaryotic cell footprints on implant surfaces. Human mesenchymal stem cells (MSCs) and Staphylococcus aureus were cultured on sample surfaces and detached using trypsin. Scanning electron microscopy confirmed that the processed surfaces did not contain any human or microbial cells. The footprints were then analysed using XPS and ToF-SIMS. XPS results showed no significant differences between the footprints, but principal component analysis of the ToF-SIMS data enabled clear separation of MSC-footprints from the S. aureus and co-culture footprints (p < 0.03). ToF-SIMS also demonstrated 'race for the surface' between proteins, which suggest surface charge (zeta-potential) dependent protein adsorption. ToF-SIMS differentiated eukaryotic and bacterial footprints and has potential for post-hoc detection of implant-related infections based on the typical ToF-SIMS spectra.

Special modes of corrosion under physiological and simulated physiological conditions

The aim of this article is to review those aspects of corrosion behaviour that are most relevant to the clinical application of implant alloys. The special modes of corrosion encountered by implant alloys are presented. The resistance of the different materials against the most typical corrosion modes (pitting corrosion, crevice corrosion and fretting corrosion) is compared, together with observations of metal ion release from different biomaterials. A short section is dedicated to possible galvanic effects in cases when different types of materials are combined in a biomedical device. The different topics covered are introduced from the viewpoint of materials science, and then placed into the context of medicine and clinical experience.

An analysis of the in vivo deterioration of Co-Cr-Mo implants through wear and corrosion

The degradation of Co-Cr-Mo ASTM F75-92 hip implants after a harvesting period of 81 months in sheep was investigated. Hip prostheses and tissue samples were obtained from a medical study involving total hip arthroplasty of the cemented type in 12 sheep. Upon euthanasia, the explants were retrieved for analyses of the surfaces and evidence of degradation, while tissue samples from the interface regions were harvested for chemical analysis and evidence of Co, Cr, and Mo contents. Clear evidence of wear and corrosion was detected. Results also indicated that the modes of metal transport through the poly(methyl methacrylate) bone cement play an important role as the surface degradation mechanisms of the metal. The results are being discussed in terms of electrochemical and triboelectrochemical behaviour of the Co-Cr-Mo alloy.

Influence of surface self-modification in Ringer's solution on the passive behavior of titanium

The influence of the spontaneous surface modification of titanium by exposure to Ringer's solution at open-circuit conditions on the passive behavior was studied. The electrochemical behavior of Ti was compared in a simple NaCl and in Ringer's physiological solution. Potentiodynamic polarization curves show significantly higher passive current densities in Ringer's solution as compared with the simple saline solution. Furthermore, impedance spectra measured at the open-circuit potential as a function of time indicate that in saline solution a long-term exposure over some days leads to a strong increase of the protectiveness of the passive film. This improvement of the passive behavior cannot be observed in Ringer's solution, but a strong modification of the passive film/electrolyte interface can be seen in the impedance spectra. The changes in the impedance spectra can be correlated with the results observed by surface characterization regarding the morphology (scanning electron microscopy) and chemical composition of the surface (X-ray photoelectron spectroscopy). In agreement with previous work by others, a spontaneous modification of the surface of Ti by Ca and P species was observed. The composition of the Ca/P precipitates changes as a function of time, indicating a slow formation of a hydroxyapatite-like deposit layer on the surface. The results of the present work indicate that the formation of the outer Ca-P deposit layer on the passive Ti surface (which is beneficial for the biological performance) hinders the normal aging of the passive TiO(2). Even though the protectiveness of the passive film can be considered as high also in Ringer's solution, significantly higher passive dissolution rates (i.e., higher metal-ion release) for Ti exposed to Ringer's solution can be expected as compared with a simple saline solution.

Timing of growth faltering in rural Malawi

AIM

To determine the timing of growth faltering among under 3 year old children.

METHODS

Prospective population based cohort study in Lungwena, rural Malawi, southeast Africa. A total of 767 live born babies were regularly visited from birth until 3 years of age. Weight, height, and mid upper arm circumference were measured at monthly intervals until 18 months and at three month intervals thereafter. Growth charts were constructed using the LMS method and comparisons made to two international databases: the traditional United States National Center for Health Statistics/World Health Organisation (NCHS/WHO) reference and the recently developed 2000 Centers for Disease Control (CDC) growth reference.

RESULTS

Compared to the 2000 CDC reference population, newborns in Lungwena were on average 2.5 cm shorter and 510 g lighter. On a population level, height faltering was present at birth and continued throughout the first three years. Weight faltering, on the other hand, occurred mainly between 3 and 12 months of age. At 36 months, the mean weight and height of the study children were 2.3 kg and 10.5 cm lower than those of the reference population, respectively. The results remained essentially similar when the comparisons were made to the NCHS/WHO reference.

CONCLUSIONS

The fact that weight and height faltering do not follow identical time patterns suggests that they may have different origin and determinants. Further studies on the aetiology of height faltering and different approaches to preventive interventions are needed.

Incidence of occupational asthma by occupation and industry in Finland

BACKGROUND

Systematic research on occupation or industry-specific incidence of occupational asthma (OA) is sparse. We calculated the incidence of notified OA by occupation, industry and causative agent in Finland for the years 1989-95.

METHODS

The numbers of cases of reported OA were retrieved from the Finnish Registry of Occupational Diseases for the population between 20 and 64 years of age. The numbers of employed workers were retrieved from Statistics Finland. Incidence rates were calculated for each occupation, industry and the total workforce.

RESULTS

Altogether 2602 cases of OA were notified and the mean annual incidence rate was 17.4 cases/100,000 employed workers. The incidence rate was the highest in bakers, other painters and lacquerers, veterinary surgeons, chemical workers, farmers, animal husbandry workers, other food manufacturing workers, welders, plastic product workers, butchers and sausage makers, and floor layers. Cases caused by animal epithelia, hairs and secretions or flours, grains, and fodders accounted for 60% of the total.

CONCLUSIONS

Estimation of occupation and industry-specific incidence rates forms the basis for successful prevention of OA, but necessitates collection of data over several years from well-established surveillance systems.

Generation of bovine immune colostrum against Streptococcus mutans and Streptococcus sobrinus and its effect on glucose uptake and extracellular polysaccharide formation by mutans streptococci

Due to potential side-effects of active immunization by cariogenic mutans streptococci, oral administration of passively-derived antibodies could be a more acceptable way to reduce colonization and virulence of these microorganisms in human dentition. The aim of this study was to produce antistreptococcal immunoglobulins into bovine colostrum and explore the possible antibacterial mechanisms of these immunoglobulins against mutans streptococci. Specific serum IgG antibodies to whole cell antigens of both Streptococcus mutans and Streptococcus sobrinus increased rapidly in cows during immunization and were high also in the final whey-product. Low concentration (0.5% w/v) of bovine immune preparation inhibited significantly the incorporation of [14C]glucose by both S. mutans and S. sobrinus. Higher concentration (> 1%) was needed to inhibit the glucosyltransferase or fructosyltransferase activities of these bacteria. No such inhibitory effects were observed with the control preparation from the non-immunized cows. Our results indicate that bovine immune colostrum has a significant inhibitory potential against mutans streptococci, apparently dependent on the presence of specific IgG antibodies against S. mutans and S. sobrinus.

Interaction of genetic and environmental factors in the pathogenesis of insulin-dependent diabetes mellitus

The current concept of the pathogenesis of insulin-dependent diabetes mellitus (IDDM) is based on the view that environmental factors, either alone or in combination, trigger in a genetically, susceptible individual an autoimmune process which leads to the destruction of the insulin-secreting beta cells. The identification of environmental risk factors for IDDM is of utmost importance with regard to possibilities for implementing preventive measures. Studies on the interaction between genetic and environmental factors may be complicated by the observations that genetic markers, e.g. HLA risk alleles, may vary from one population to another, and combinations of predisposing genes may differ between populations. In addition, the role of a given environmental trigger in initiating the autoimmune process may be variable in various individuals depending on the genetic set-up and other host-related characteristics. As prevention trials are already being initiated, and genetic screening is essential in the identification of individuals at increased risk of IDDM, it is crucial to learn more about the interaction of genetic and environmental factors in this disease.

Immunoaffinity chromatographic purification of cellobiohydrolase II mutants from recombinant trichoderma reesei strains devoid of major endoglucanase genes

Efficient purification of Trichoderma reesei cellobiohydrolase II (CBHII) requires the use of affinity chromatography based on a substrate analogue. Due to altered substrate binding, the purification of many active-site mutants of CBHII from the complex fungal culture media represents a considerable challenge. Here we describe a combination of two approaches to facilitate the purification: the first is based on the construction of novel engineered T. reesei strains devoid of the major contaminating endoglucanases, and the second uses immunoaffinity chromatography as the final purification step. Two different procedures for the preparation of the antibody matrix were tested. Crosslinking of the monoclonal antibody to Protein G matrix instead of the conventional immobilization via cyanogen bromide increased the binding efficiency. Three different active-site mutants of CBHII bound to the immunoaffinity column in neutral pH and were eluted in pH 2.7. The purity of the CBHII mutant preparations was tested using small chromophoric substrates and hydroxyethyl cellulose, which are hydrolyzed by many other cellulases but not by CBHII. The immunoaffinity column purified the CBHII mutants over 800-fold in a single step and resulted in homogeneous protein preparations free of proteolytically cleaved forms of CBHII. The use of the double replacement T. reesei production strains, especially the one lacking the genes coding for both the endogeneous CBHII and the endoglucanase II (EGII), helped to reduce the total endoglucanase activity in the preparations.

Dual task performance after focal cerebral lesions and closed head injuries

The aim of this study was to demonstrate that focal frontal lobe lesions and closed head injuries cause a deficit in the deliberate minimizing of dual task decrements that follow when two separate tasks should be done concurrently. In single tasks, subjects counted backwards and cancelled visual targets as quickly and accurately as possible on separate 1 min trials. In the dual task, they were required to do both tasks simultaneously, taking care that performance on neither task would be notably more impaired than on the other, as only the performance showing a larger percentage decrement from the corresponding single task performance was taken into account as the result of the test. Patients with acute closed head injury displayed more pronounced dual task decrement than the controls. This deficit was not secondary to inefficiency on the single tasks but was related to the depth of coma at admission, the acuteness of injury and age. Contrary to expectation, patients with focal frontal lobe lesions or patients with subacute closed head injury did not demonstrate abnormal dual task decrement.

Subgroup differentiation and subgroup bias among Latinos as a function of familiarity and positive distinctiveness

The existence of subgroup differentiation and its impact on the development of in-group bias were explored among Latinos. Consistent with prior evidence, Cubans, Mexicans, and Puerto Ricans were more likely than Anglos to distinguish between Latino subgroups. However, Latinos did not distinguish equally between Cubans, Mexicans, and Puerto Ricans. Latinos differentiated their own subgroup from others but were no more likely than Anglos to differentiate between Latino subgroups to which they did not belong. Latinos even regarded the term Hispanic as more applicable to members of their own subgroup than to members of other subgroups. This tendency among Latinos to view their own subgroup as distinct from others was also linked to a bias for fellow subgroup members but not for Latinos overall. Moreover, results suggested that subgroup differentiation was based more on a desire for positive distinctiveness than on familiarity with members of different Latino subgroups.

Subgroup differentiation and subgroup bias among Latinos as a function of familiarity and positive distinctiveness

The existence of subgroup differentiation and its impact on the development of in-group bias were explored among Latinos. Consistent with prior evidence, Cubans, Mexicans, and Puerto Ricans were more likely than Anglos to distinguish between Latino subgroups. However, Latinos did not distinguish equally between Cubans, Mexicans, and Puerto Ricans. Latinos differentiated their own subgroup from others but were no more likely than Anglos to differentiate between Latino subgroups to which they did not belong. Latinos even regarded the term Hispanic as more applicable to members of their own subgroup than to members of other subgroups. This tendency among Latinos to view their own subgroup as distinct from others was also linked to a bias for fellow subgroup members but not for Latinos overall. Moreover, results suggested that subgroup differentiation was based more on a desire for positive distinctiveness than on familiarity with members of different Latino subgroups.

Overexpression of p53 and long-term survival in colon carcinoma

Survival analysis of 144 histologically confirmed cases of colon carcinoma diagnosed in a 12 year period (1971-82) at the Tampere University Hospital was performed to test the hypothesis that p53 overexpression is associated with a poor clinical outcome. Immunohistochemical staining of paraffin-embedded sections using a polyclonal antibody CM-1 against p53 protein was performed to identify aberrant expression of the p53 tumour-suppressor gene. Sixty-nine per cent of the tumours (100/144) showed overexpression of the p53 protein. The prevalence of p53 overexpression was independent of age and sex of the patient and subsite of the tumour, but was slightly, although not statistically significantly, higher in advanced than in localised tumours. Overexpression was associated with a higher S-phase fraction. Some indication of a larger proportion of aneuploid tumours among those with overexpression was also observed, although this finding did not reach statistical significance. Significantly reduced patient survival for tumours with p53 overexpression was found. Patients with p53-overexpressing tumours had a corrected 5 year survival rate of 37% compared with 58% among patients whose tumours had normal expression of p53. The corresponding 10 year rates were 34% and 54%. In the multivariate analysis using a Cox model, the survival difference was independent of age and sex of the patient, as well as of subsite and stage of the tumour. Furthermore, the effect of p53 overexpression remained after controlling for flow cytometric parameters in an analysis of a subset of tumours. Thus, p53 overexpression appears to be a useful prognostic indicator in colon carcinoma.

1H NMR studies on human plasma lipids from newborn infants, healthy adults, and adults with tumors

The 1H NMR spectra of the lipid region of human plasma from healthy adults, neonates, and patients with malignant and nonmalignant tumors have been recorded on a JNM-GX400 FT spectrometer operating at 399.6 MHz for protons. The chemical shifts of methylene and methyl groups of plasma lipids were measured with respect to the higher field component of the methyl proton resonance of the lactate molecule. The results show that there are changes in the chemical shifts of the methylene proton resonances among the plasma from healthy adults, adults with tumors, and neonates. The shifts observed in the case of cancer patients and neonates are in the direction opposite to the shift measured from the plasma of healthy adults. Thus, the observed changes cannot be explained by the activity in the cell proliferation of tissues which is high in the cases of both healthy neonates and patients with malignant tumors, but they most probably reflect the different lipoprotein compositions of neonates, healthy adults, and adults with tumors.