Showing papers by "University of Gothenburg published in 1999"

Role of PDGF-B and PDGFR-beta in recruitment of vascular smooth muscle cells and pericytes during embryonic blood vessel formation in the mouse.

Abstract: Development of a vascular system involves the assembly of two principal cell types - endothelial cells and vascular smooth muscle cells/pericytes (vSMC/PC) - into many different types of blood vessels. Most, if not all, vessels begin as endothelial tubes that subsequently acquire a vSMC/PC coating. We have previously shown that PDGF-B is critically involved in the recruitment of pericytes to brain capillaries and to the kidney glomerular capillary tuft. Here, we used desmin and alpha-smooth muscle actin (ASMA) as markers to analyze vSMC/PC development in PDGF-B-/- and PDGFR-beta-/- embryos. Both mutants showed a site-specific reduction of desmin-positive pericytes and ASMA-positive vSMC. We found that endothelial expression of PDGF-B was restricted to immature capillary endothelial cells and to the endothelium of growing arteries. BrdU labeling showed that PDGFR-beta-positive vSMC/PC progenitors normally proliferate at sites of endothelial PDGF-B expression. In PDGF-B-/- embryos, limb arterial vSMC showed a reduced BrdU-labeling index. This suggests a role of PDGF-B in vSMC/PC cell proliferation during vascular growth. Two modes of vSMC recruitment to newly formed vessels have previously been suggested: (1) de novo formation of vSMC by induction of undifferentiated perivascular mesenchymal cells, and (2) co-migration of vSMC from a preexisting pool of vSMC. Our data support both modes of vSMC/PC development and lead to a model in which PDGFR-beta-positive vSMC/PC progenitors initially form around certain vessels by PDGF-B-independent induction. Subsequent angiogenic sprouting and vessel enlargement involves PDGF-B-dependent vSMC/PC progenitor co-migration and proliferation, and/or PDGF-B-independent new induction of vSMC/PC, depending on tissue context.

Neutrophil Recruitment by Human IL-17 Via C-X-C Chemokine Release in the Airways

Abstract: IL-17 is a recently discovered cytokine that can be released from activated human CD4+ T lymphocytes. This study assessed the proinflammatory effects of human (h) IL-17 in the airways. In vitro, hIL-17 increased the release of IL-8 in human bronchial epithelial and venous endothelial cells, in a time- and concentration-dependent fashion. This effect of hIL-17 was inhibited by cotreatment with an anti-hIL-17 Ab and was potentiated by hTNF-alpha. In addition, hIL-17 increased the expression of hIL-8 mRNA in bronchial epithelial cells. Conditioned medium from hIL-17-treated bronchial epithelial cells increased human neutrophil migration in vitro. This effect was blocked by an anti-hIL-8 Ab. In vivo, intratracheal instillation of hIL-17 selectively recruited neutrophils into rat airways. This recruitment of neutrophils into the airways was inhibited by an anti-hIL-17 Ab and accompanied by increased levels of rat macrophage inflammatory protein-2 (rMIP-2) in bronchoalveolar lavage (BAL) fluid. The BAL neutrophilia was also blocked by an anti-rMIP-2 Ab. The effect of hIL-17 on the release of hIL-8 and rMIP-2 was also inhibited by glucocorticoids, in vitro and in vivo, respectively. These data demonstrate that hIL-17 can specifically and selectively recruit neutrophils into the airways via the release of C-X-C chemokines from bronchial epithelial cells and suggest a novel mechanism linking the activation of T-lymphocytes to recruitment of neutrophils into the airways.

Enriched environment increases neurogenesis in the adult rat dentate gyrus and improves spatial memory.

Abstract: The fetal and even the young brain possesses a considerable degree of plasticity. The plasticity and rate of neurogenesis in the adult brain is much less pronounced. The present study was conducted to investigate whether housing conditions affect neurogenesis, learning, and memory in adult rats. Three-month-old rats housed either in isolation or in an enriched environment were injected intraperitoneally with bromodeoxyuridine (BrdU) to detect proliferation among progenitor cells and to follow their fate in the dentate gyrus. The rats were sacrificed either 1 day or 4 weeks after BrdU injections. This experimental paradigm allows for discrimination between proliferative effects and survival effects on the newborn progenitors elicited by different housing conditions. The number of newborn cells in the dentate gyrus was not altered 1 day after BrdU injections. In contrast, the number of surviving progenitors 1 month after BrdU injections was markedly increased in animals housed in an enriched environment. The relative ratio of neurogenesis and gliogenesis was not affected by environmental conditions, as estimated by double-labeling immunofluorescence staining with antibodies against BrdU and either the neuronal marker calbindin D28k or the glial marker GFAp, resulting in a net increase in neurogenesis in animals housed in an enriched environment. Furthermore, we show that adult rats housed in an enriched environment show improved performance in a spatial learning test. The results suggest that environmental cues can enhance neurogenesis in the adult hippocampal region, which is associated with improved spatial memory.

Responses of tundra plants to experimental warming:meta‐analysis of the international tundra experiment

Abstract: The International Tundra Experiment (ITEX) is a collaborative, multisite experiment using a common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems. ITEX was designed specifically to examine variability in arctic and alpine species response to increased temperature. We compiled from one to four years of experimental data from 13 different ITEX sites and used meta-analysis to analyze responses of plant phenology, growth, and reproduction to experimental warming. Results indicate that key phenological events such as leaf bud burst and flowering occurred earlier in warmed plots throughout the study period; however, there was little impact on growth cessation at the end of the season. Quantitative measures of vegetative growth were greatest in warmed plots in the early years of the experiment, whereas reproductive effort and success increased in later years. A shift away from vegetative growth and toward reproductive effort and success in the fourth treatment year suggests a shift from the initial response to a secondary response. The change in vegetative response may be due to depletion of stored plant reserves, whereas the lag in reproductive response may be due to the formation of flower buds one to several seasons prior to flowering. Both vegetative and reproductive responses varied among life-forms; herbaceous forms had stronger and more consistent vegetative growth responses than did woody forms. The greater responsiveness of the herbaceous forms may be attributed to their more flexible morphology and to their relatively greater proportion of stored plant reserves. Finally, warmer, low arctic sites produced the strongest growth responses, but colder sites produced a greater reproductive response. Greater resource investment in vegetative growth may be a conservative strategy in the Low Arctic, where there is more competition for light, nutrients, or water, and there may be little opportunity for successful germination or seedling development. In contrast, in the High Arctic, heavy investment in producing seed under a higher temperature scenario may provide an opportunity for species to colonize patches of unvegetated ground. The observed differential response to warming suggests that the primary forces driving the response vary across climatic zones, functional groups, and through time.

A screening questionnaire for Asperger syndrome and other high-functioning autism spectrum disorders in school age children.

Abstract: The high-functioning Autism Spectrum Screening Questionnaire (ASSQ) is a 27-item checklist for completion by lay informants when assessing symptoms characteristic of Asperger syndrome and other high-functioning autism spectrum disorders in children and adolescents with normal intelligence or mild mental retardation. Data for parent and teacher ratings in a clinical sample are presented along with various measures of reliability and validity. Optimal cutoff scores were estimated, using Receiver Operating Characteristic analysis. Findings indicate that the ASSQ is a useful brief screening device for the identification of autism spectrum disorders in clinical settings.

Sample purification and preparation technique based on nano-scale reversed-phase columns for the sensitive analysis of complex peptide mixtures by matrix-assisted laser desorption/ionization mass spectrometry.

Abstract: A simple reversed-phase nano-column purification and sample preparation technique is described, which markedly improves the mass spectrometric analysis of complex and contaminated peptide mixtures by matrix-assisted laser desorption/ionization (MALDI). The method is simple, fast and utilizes only low-cost disposables. After loading the sample on the column and a subsequent washing step, the analyte molecules are eluted with 50-100 nl of matrix solution directly on to the MALDI/MS target. The washing step ensures removal of a wide range of contaminants. The small bed volume of the column allows efficient sample concentration and the elution process yields very small sample spots. This simplifies the analysis and minimizes discrimination effects due to sample heterogeneity, because the desorption/ionization laser simultaneously irradiates a large portion of the sample. Taken together, these features of the method significantly improve the sensitivity for MALDI/MS analysis of contaminated peptide samples compared with the commonly used sample preparation procedures. This is demonstrated with in-gel tryptic digests of proteins from human brain that were separated by 2D gel electrophoresis. Furthermore, it is shown that with this method 2,5-dihydroxybenzoic acid (DHB) acts as an efficient matrix for peptide mapping. Both detection sensitivity and sequence coverage are comparable to those obtained with the currently preferred matrix alpha-cyano-4-hydroxycinnamic acid (CHCA). The higher stability of peptide ions generated with DHB compared with CHCA is advantageous when analyzing fragile sample molecules. Therefore, the method described here is also of interest for the use of Fourier transform ion cyclotron resonance (FT-ICR) or ion-trap mass analyzers.

Restoration of an inbred adder population

Abstract: The negative effects of inbreeding on population size are well documented in captive animals1, but there is surprisingly little evidence that genetic factors cause a decline in wild populations2,3, apart from a reported correlation of low levels of genetic variability with a high incidence of malformed or stillborn offspring4. From the point of view of conservation strategies, it is not only the effect of genetic factors on population decline that needs to be considered, but also whether introducing novel genes can prevent or reverse such a decline. Here we show that the introduction of new genes into a severely inbred and isolated population of adders (Vipera berus) halted its precipitous decline towards extinction and expanded the population dramatically.

Autologous chondrocyte transplantation.

Abstract: The intrinsic capacity of cartilage to repair chondral injuries is poor. Different techniques to induce cartilage repair with the use of extrinsic chondrogeneic cell sources have been explored in experimental models. Cells can be harvested autologously or as allografts from a healthy part of the donor tissue, isolated, expanded in vitro, and finally implanted into the defect in high densities. Pure chondrocytes, epiphyseal or mature, allogeneic or autologous, and other types of mesenchymal cells have been used. The composition and structure of the extracellular cartilage matrix are maintained through a balance of anabolic and catabolic activities controlled by the unique chondrocytes. They keep the cartilage alive; they alone maintain it and regulate it. It therefore seems important to use true committed chondrocytes to repair a local cartilaginous defect. The rational basis for the use of committed autologous chondrocytes in combination with a covering periosteal membrane in the treatment of deep cartilage defects is presented.

Microbial findings at failing implants.

Abstract: The aim of this study was to evaluate qualitative differences in the subgingival microbiota at titanium implants, ad modum Branemark, demonstrating clinical and radiographic signs of loss of supporting tissues (peri-implantitis) as compared to implants surrounded by healthy tissues. A total of 37 patients demonstrating 1 or more implants with bone loss > or = 3 threads, bleeding on probing and/or suppuration and 51 patients with clinically healthy mucosa and no bone loss were recruited for the study. In each patient subgingival bacterial samples were obtained using paper-points, and subjected to microbiological analysis by culture. The two types of clinical conditions showed distinct bacterial profiles. For implants with peri-implantitis putative periodontal pathogens, such as Porphyromonas gingivalis, Prevotella intermedia/Prevotella nigrescens and Actinobacillus actinomycetemcomitans, were found in 60% of the cases and microorganisms primarily not associated with periodontitis, such as Staphylococcus spp., enterics and Candida spp., were found in 55% of the peri-imaplant lesions. In contrast, implants surrounded by healthy tissue demonstrated a microbiota associated with periodontal health. The results indicate that the microbiota of the healthy peri-implant sulci is similar to that from corresponding conditions around teeth. However, in peri-implant areas staphylococci, enterics and yeasts were found almost as frequently as periopathogens indicating differences as compared to the microbiota around periodontitis affected teeth. A microbiological diagnosis may therefore be of guidance for the choice of antimicrobial treatment in patients with peri-implant infection.

Unmyelinated afferents constitute a second system coding tactile stimuli of the human hairy skin.

Abstract: Unmyelinated afferents constitute a second system coding tactile stimuli of the human hairy skin. Impulses were recorded from unmyelinated afferents innervating the forearm skin of human subjects u...

Branemark Novum : a new treatment concept for rehabilitation of the edentulous mandible. Preliminary results from a prospective clinical follow-up study

Abstract: Background: Branemark fixtures were originally prescribed to be placed in two surgical stages. During the past years, reports on the placement of machined titanium implants in a one-stage procedure have been published, and the results have been encouraging. Recendy there has been considerable interest in early or immediate loading. Purpose: The purpose of this article is to report the preliminary clinical results of a new method for implant treatment of the edentulous mandible. The new protocol involves prefabricated components and surgical guides, elimination of the prosthetic impression procedure and attachment of the permanent fixed bridge on the day of implant placement. Methods: Fifty patients (26 males, 24 females) received 150 Branemark Novum implants and were followed from 6 months to 3 years after implant placement. Bone width and height were determined preoperatively with the use of radiographs. The jaw was reduced in height to accommodate three special 5-mm wide implants. Precise implant positioning was accomplished with special drilling templates. Drill guides were placed over the drilling templates during site preparation using a series of specially designed drills. After the mucosa had been sutured back into position, a prefabricated titanium lower bar was connected with titanium screws to the transmucosal fixture. Another titanium bar was then attached by the prosthodontist, and a bite registration was performed. The bridge was attached to the upper bar. The permanent reconstruction was provided to the patient later the same day. Results: Three implants were lost to follow-up and three failed, resulting in an overall survival rate of 98%. One prosthesis failed, leaving a prosthetic survival rate of 98%. The average treatment time was approximately 7 hours. At the baseline examination, the marginal bone level was 0.72 mm below the reference point. The average marginal bone loss was 0.2 mm per year and 0.26 mm between the 3-month and 1-year control visits. The accumulated mean bone loss, including baseline, was-1.25 mm. A patient questionnaire demonstrated that 94% of the patients did not experience any discomfort during treatment and all patients would recommend the procedure to others. Conclusion: The results of this study indicate that the precise surgical and prosthetic protocol allows successful prosthetic rehabilitation of mandibular edentulism and that the permanent reconstruction can be provided to the patient on the day of fixture surgery.

Ultraviolet colour variation influences blue tit sex ratios

Abstract: Brilliant blue and violet structural colours are common plumage ornaments in birds, but their signalling functions are poorly understood1. This may be because birds also communicate in ultraviolet (UV-A) wavelengths (320–400 nm)2,3,4,5, invisible to humans, but a strong spectral component of many structural colours6. From a wild population of blue tits—Parus caeruleus, sexually dimorphic primarily in the ultraviolet7,8—we report experimental evidence that females skew the sex ratio of their offspring in response to the ultraviolet plumage ornamentation of their mates. Masking male ultraviolet reflectance reversed a positive correlation between reflectance and brood sex ratio observed in control pairs, demonstrating a causal effect of male ultraviolet ornamentation on offspring sex ratio. Ultraviolet reflectance also predicted male survival to the following breeding season, suggesting that it serves as a viability indicator. When taken together with ecological effects (laying date, nesting area), our experiments reveal that an unexpected amount of control exists over the primary sex ratio in birds, suggesting that chromosomal sex determination may not constrain the sex ratios of multiparous vertebrates.

Developmental coordination disorder in Swedish 7-year-old children.

Abstract: Objective To estimate the prevalence, comorbidity, and outcome in developmental coordination disorder (DCD). Method In this population study of 7-year-olds undergoing individual examination plus teacher and parent interviews, children were followed up at ages 8, 9, and 10 years. Results Severe DCD occurred in 4.9% and moderate DCD in another 8.6%. Boy-girl ratios ranged from 4:1 to 7:1. Children with severe and moderate DCD did not differ from each other on any measure, but both groups were clearly separated from children without DCD with respect to associated attention deficit symptoms, Asperger's disorder symptoms, school dysfunction scores, and outcome. Approximately half of all children with DCD had moderate to severe symptoms of attention-deficit/hyperactivity disorder (ADHD). Conclusions DCD is a common problem, and it is strongly associated with ADHD symptoms. A diagnosis of DCD at age 7 years predicts DCD at age 8 years and restricted reading comprehension at age 10 years. Clinicians need to acquaint themselves with DCD and its comorbidity so that they can provide better services to affected children.

Abnormal reaction to central nervous system injury in mice lacking glial fibrillary acidic protein and vimentin.

Abstract: In response to injury of the central nervous system, astrocytes become reactive and express high levels of the intermediate filament (IF) proteins glial fibrillary acidic protein (GFAP), vimentin, and nestin. We have shown that astrocytes in mice deficient for both GFAP and vimentin (GFAP−/−vim−/−) cannot form IFs even when nestin is expressed and are thus devoid of IFs in their reactive state. Here, we have studied the reaction to injury in the central nervous system in GFAP−/−, vimentin−/−, or GFAP−/−vim−/− mice. Glial scar formation appeared normal after spinal cord or brain lesions in GFAP−/− or vimentin−/− mice, but was impaired in GFAP−/−vim−/− mice that developed less dense scars frequently accompanied by bleeding. These results show that GFAP and vimentin are required for proper glial scar formation in the injured central nervous system and that some degree of functional overlap exists between these IF proteins.

APOE-ε4 count predicts age when prevalence of AD increases, then declines: The Cache County Study

Abstract: Objective: To examine the prevalence of Alzheimer’s disease (AD) and other dementias in relation to age, education, sex, and genotype at APOE. Recent studies suggest age heterogeneity in the risk of AD associated with the APOE genotype and a possible interaction between APOE-e4 and female sex as risk factors. We studied these topics in the 5,677 elderly residents of Cache County, Utah, a population known for long life expectancy and high participation rates. Methods: We screened for dementia with a brief cognitive test and structured telephone Dementia Questionnaire, then examined all individuals with apparent cognitive symptoms and a sample of others. We estimated age-specific prevalence of AD and other dementias and used multiple logistic regression models to describe relation of AD prevalence to age, sex, education, and APOE genotype. Results: We found 335 demented individuals, 230 (69%) with definite, probable, or possible AD (positive predictive value versus autopsy confirmation 85%). The adjusted prevalence estimate for AD was 6.5% and for all dementias 9.6%. After age 90, the adjusted prevalence estimate for AD was 28% and for all dementias 38%. Regression models showed strong variation in AD prevalence with age, sex, education, and number of e4 alleles (effect of e2 not significant). Models were improved by a term for age-squared (negative coefficient) and by separate terms for interaction of age with presence of one or two e4 alleles. An association of AD with female sex was ascribable entirely to individuals with e4. Conclusions: In participants with no e4 alleles, the age-specific prevalence of AD reached a maximum and then declined after age 95. In e4 heterozygotes a similar maximum was noted earlier at age 87, in homozygotes at age 73. Female sex was a risk factor for AD only in those with e4. The e4 allele accounted for 70% of the population attributable risk for AD.

Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation.

Abstract: The accumulation of compatible solutes, such as glycerol, in the yeast Saccharomyces cerevisiae, is a ubiquitous mechanism in cellular osmoregulation. Here, we demonstrate that yeast cells control glycerol accumulation in part via a regulated, Fps1p-mediated export of glycerol. Fps1p is a member of the MIP family of channel proteins most closely related to the bacterial glycerol facilitators. The protein is localized in the plasma membrane. The physiological role of Fps1p appears to be glycerol export rather than uptake. Fps1 delta mutants are sensitive to hypo-osmotic shock, demonstrating that osmolyte export is required for recovery from a sudden drop in external osmolarity. In wild-type cells, the glycerol transport rate is decreased by hyperosmotic shock and increased by hypo-osmotic shock on a subminute time scale. This regulation seems to be independent of the known yeast osmosensing HOG and PKC signalling pathways. Mutants lacking the unique hydrophilic N-terminal domain of Fps1p, or certain parts thereof, fail to reduce the glycerol transport rate after a hyperosmotic shock. Yeast cells carrying these constructs constitutively release glycerol and show a dominant hyperosmosensitivity, but compensate for glycerol loss after prolonged incubation by glycerol overproduction. Fps1p may be an example of a more widespread class of regulators of osmoadaptation, which control the cellular content and release of compatible solutes.

Autism: not an extremely rare disorder

Abstract: Objective: To study autism over time in order to ascertain whether there has been an increase in its prevalence in recent years Method: All English language papers on the prevalence of autism were reviewed Ten of the studies retrieved were not used in the final analysis because they did not meet full criteria for inclusion in the review The remaining 20 studies, published between 1966 and 1997, were subdivided into US studies (n = 2) and non-US studies (n= 18), and the latter group was subdivided into four 8-year periods Results: The early studies yielded prevalence rates of under 05 in 1000 children, whereas the later ones showed a mean rate of about 1 in 1000 There was a marked difference in prevalence rates between those studies that included some children born before 1970 (low rates) and those that included only children born in 1970 and after (high rates) This is probably due to the lower rates obtained by use of criteria strictly based on Kanner's description of his syndrome The US studies reported atypically low rates There was a highly significant estimated increase with calendar year in the non-US studies (38%, per year) Conclusion: It is concluded that autism is considerably more common than was previously believed The possible reasons for the higher reported rates are discussed

Autism and Hearing Loss

Abstract: A group of 199 children and adolescents (153 boys, 46 girls) with autistic disorder was audiologically evaluated. Mild to moderate hearing loss was diagnosed in 7.9% and unilateral hearing loss in 1.6% of those who could be tested appropriately. Pronounced to profound bilateral hearing loss or deafness was diagnosed in 3.5% of all cases, representing a prevalence considerably above that in the general population and comparable to the prevalence found in populations with mental retardation. Hearing deficits in autism occurred at similar rates at all levels of intellectual functioning, so it does not appear that the covariation with intellectual impairment per se can account for all of the variance of hearing deficit in autism. Hyperacusis was common, affecting 18.0% of the autism group and 0% in an age-matched nonautism comparison group. In addition, the rate of serous otitis media (23.5%) and related conductive hearing loss (18.3 %) appeared to be increased in autistic disorder. The study emphasizes the need for auditory evaluation of individuals with autism in order to refer those with pronouced to profound hearing loss for aural habilitation and to follow those with mild to moderate hearing loss because of the risk of deterioration.

Hypothalamic arousal, insulin resistance and Type 2 diabetes mellitus.

Abstract: Summary Aims Type 2 diabetes mellitus (DM) develops when insulin resistance overcomes the capacity of compensatory insulin secretion. Insulin resistance may be induced via psychoneuroendocrine pathways, a possibility which has received little previous attention. Methods We have used salivary cortisol measurements to monitor the activity of the hypothalamic–pituitary–adrenal (HPA) axis, the major controller of hormones involved in the regulation of peripheral insulin sensitivity under everyday conditions. The influence of external challenges, as well as the sensitivity of feedback regulation, were followed in randomly selected middle-aged population samples. Results In health there is a rhythmicity of cortisol secretion, with a high plasticity and efficient feedback control. In contrast, a group of subjects were identified with a flat, rigid day curve and poor feedback control, who showed consistent abnormalities in stress-related cortisol secretion, including inhibited secretions of sex steroids and growth hormone; insulin resistance; abdominal obesity; elevated leptin levels; hyperglycaemia; dyslipidaemia and hypertension with elevated heart rate. The endocrine abnormalities are probably responsible for the anthropometric and metabolic abnormalities. The circulatory perturbations seem to be induced by a parallel activation of the central sympathetic nervous system suggesting an ‘hypothalamic arousal syndrome’, gradually developing into an independent risk for disease. An associated cluster of environmental factors, including psychosocial and socio-economic stress, traits of depression and anxiety, alcohol consumption and smoking, all factors known to activate hypothalamic centres, has been identified. A polymorphism of the glucocorticoid receptor gene, with 13.7% homozygotes in the male Swedish population, parallels receptor dysfunction, and may be responsible for the associated insulin resistance, central obesity and hypertension. Conclusions This is the first detailed examination of psychoneuroendocrinological processes in the natural environment on a population basis in relation to somatic health. The results suggest that an hypothalamic arousal syndrome, with parallel activation of the HPA axis and the central sympathetic nervous system, is responsible for development of endocrine abnormalities, insulin resistance, central obesity, dyslipidaemia and hypertension, leading to frank disease, including Type 2 DM. We suggest that this syndrome is probably based on environmental pressures in genetically susceptible individuals. Diabet. Med. 16, 373–383 (1999)

Extended Framework for Modeling Choice Behavior

Abstract: We review the case against the standard model of rational behavior and discuss the consequences of various ‘anomalies’ of preference elicitation. A general theoretical framework that attempts to disentangle the various psychological elements in the decision-making process is presented. We then present a rigorous and general methodology to model the theoretical framework, explicitly incorporating psychological factors and their influences on choices. This theme has long been deemed necessary by behavioral researchers, but is often ignored in demand models. The methodology requires the estimation of an integrated multi-equation model consisting of a discrete choice model and the latent variable model system. We conclude with a research agenda to bring the theoretical framework into fruition.

Differential diagnosis and treatment strategies for biologic complications and failing oral implants: a review of the literature.

Abstract: The aim of this article was to review the literature on differential diagnosis and treatment of biologic complications and failing implants All types of publications, with the exception of abstracts, published in English up to December 1998, were included A multi-layered search strategy was used Controlled clinical trials (CCTs) were searched in the Cochrane Oral Health Group's Specialized Register of Trials This database contains all CCTs identified in MEDLINE and EMBASE PubMed was searched using various key words and the "related articles" feature All identified publications were obtained and none were excluded Infection, impaired healing, and overload are considered the major etiologic factors for the loss of oral implants Only a few clinical and animal investigations were found that tested the validity of the proposed therapeutic approaches The treatment of failing implants is still based mainly on empirical considerations, often derived from periodontal research, from data extrapolated from in vitro findings, or from anecdotal case reports performed on a trial-and-error basis

Core Promoter Mutations and Genotypes in Relation to Viral Replication and Liver Damage in East Asian Hepatitis B Virus Carriers

Abstract: Virus load and liver damage, as measured by quantitative polymerase chain reaction and histology activity index, were related to genotype and core promoter mutations in 43 chronic hepatitis B virus (HBV) carriers of East Asian origin. T-1762 mutants were more frequent in genotype C strains and were associated with more inflammation (P=.0036) and fibrosis (P=.0088) of the liver but not with hepatitis B e antigen (HBeAg) status or virus load. Conversely, precore mutations were associated with less liver inflammation (P=. 08), which was linked to HBeAg negativity and lower viral replication. Carriers with genotype C were more often HBeAg positive (P=.03) with precore wild type strains and more-severe liver inflammation (P=.009) than were those with genotype B. These findings suggest that pathogenic differences between genotypes may exist and that the T-1762 mutation may be useful as a marker for progressive liver damage but seem to contradict that down-regulation of HBeAg production is the major effect of this mutation.

In Search of Smoking Guns: What Makes Income Inequality Vary over Time in Different Countries?

Abstract: We investigate the forces affecting the distribution of income by analyzing an unbalanced panel of information for 16 industrialized countries for the years 1966 through 1994. Income inequality is measured with the Gini coefficient of equivalent disposable income; individuals are the unit of analysis; the statistical analysis uses panel methods. The results suggest that many factors affect the development of income inequality. Some factors are strictly economic: A decreased industrial sector generally fosters inequality, and some support is found for the view that increased trade of manufactured goods from developing countries is also a factor. Other forces are outside a strictly defined market sphere: Low inequality is found when a large proportion of the labor force belongs to a trade union and also when there is a large public sector. In addition, demographic circumstances are important, since the proportion of the population under age 15 has a positive effect on inequality. We find, however, no association between the unemployment rate and inequality