Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancer.

Transition from traditional high-fiber to Western diets in urbanizing communities of Sub-Saharan Africa is associated with increased risk of non-communicable diseases (NCD), exemplified by colorectal cancer (CRC) risk. To investigate how urbanization gives rise to microbial patterns that may be amenable by dietary intervention, we analyzed diet intake, fecal 16 S bacteriome, virome, and metabolome in a cross-sectional study in healthy rural and urban Xhosa people (South Africa). Urban Xhosa individuals had higher intakes of energy (urban: 3,578 ± 455; rural: 2,185 ± 179 kcal/d), fat and animal protein. This was associated with lower fecal bacteriome diversity and a shift from genera favoring degradation of complex carbohydrates (e.g., Prevotella) to taxa previously shown to be associated with bile acid metabolism and CRC. Urban Xhosa individuals had higher fecal levels of deoxycholic acid, shown to be associated with higher CRC risk, but similar short-chain fatty acid concentrations compared with rural individuals. Fecal virome composition was associated with distinct gut bacterial communities across urbanization, characterized by different dominant host bacteria (urban: Bacteriodota; rural: unassigned taxa) and variable correlation with fecal metabolites and dietary nutrients. Food and skin microbiota samples showed compositional differences along the urbanization gradient. Rural-urban dietary transition in South Africa is linked to major changes in the gut microbiome and metabolome. Further studies are needed to prove cause and identify whether restoration of specific components of the traditional diet will arrest the accelerating rise in NCDs in Sub-Saharan Africa.

Weak latitudinal trends in reproductive traits of Afromontane forest trees.

BACKGROUND AND AIMS: Is the increase in species diversity patterns towards lower latitudes, linked to reproductive traits? Plant reproductive organs influence reproductive isolation and hence species divergence. Abiotic differences between temperate and tropical regions can also directly impact on plant reproductive traits. Here we provide a novel overview of southern hemisphere, Afromontane forest tree taxonomical patterns and ask whether reproductive traits relate to latitude, while accounting for environmental (tree height) and evolutionary (biogeographical affinity) selective forces. METHODS: We compiled a novel dataset with a) flower colour, size and pollination syndrome and b) fruit colour, size and dispersal syndrome for 331 tree species found in six Afromontane forest regions. We categorised each species into latitudinal distribution using these six regions, spanning the southern Cape (34º S) to Mount Kenya (0º S). Additionally, we gathered maximum tree height (m) for each species and determined the global distribution of all 196 tree genera (Afrotropical, Palaeotropical or Pantropical). KEY RESULTS: Species, genera and families showed a general decrease in richness away from tropical and subtropical forests towards warm temperate forests. Southern Afrotemperate forests (the furthest south) had the highest tree endemism. There was no relationship between latitude and the reproductive traits tested here. Biogeographical affinity related to fruit colour and dispersal syndrome, with palaeotropical genera showing relative increases in black-purple fruit colour compared to pantropical genera and palaeotropical genera showing relative increases in biotic seed dispersal compared to Afrotropical genera, which showed higher relative abiotic seed dispersal. Taller trees had a higher chance to be wind or insect pollinated (compared to bird pollinated) and had larger fruits. CONCLUSIONS: Latitude explained patterns in Afromontane tree taxonomical diversity, however tree reproductive traits did not relate to latitude. We suggest that phylogenetic conservatism or convergence, or both, explain the reported patterns.

Human Respiratory Syncytial Virus Subgroup A and B Infections in Nasal, Bronchial, Small-Airway, and Organoid-Derived Respiratory Cultures.

Human respiratory syncytial virus (HRSV) is the leading cause of bronchiolitis in infants. Two subgroups of HRSV (A and B) routinely cocirculate. Most research has been performed with HRSV-A strains because these are easier to culture than HRSV-B strains. In this study, we aimed to compare the replicative fitness and HRSV-induced innate cytokine responses of HRSV-A and HRSV-B strains in disease-relevant cell culture models. We used two recombinant (r) clinical isolate-based HRSV strains (A11 and B05) and one recombinant laboratory-adapted HRSV strain (A2) to infect commercially available nasal, bronchial, and small-airway cultures. Epithelial cells from all anatomical locations were susceptible to HRSV infection despite the induction of a dominant type III interferon response. Subgroup A viruses disseminated and replicated faster than the subgroup B virus. Additionally, we studied HRSV infection and innate responses in airway organoids (AOs) cultured at air-liquid interface (ALI). Results were similar to the commercially obtained bronchial cells. In summary, we show that HRSV replicates well in cells from both the upper and the lower airways, with a slight replicative advantage for subgroup A viruses. Lastly, we showed that AOs cultured at ALI are a valuable model for studying HRSV ex vivo and that they can be used in the future to study factors that influence HRSV disease severity.IMPORTANCE Human respiratory syncytial virus (HRSV) is the major cause of bronchiolitis and pneumonia in young infants and causes almost 200,000 deaths per year. Currently, there is no vaccine or treatment available, only a prophylactic monoclonal antibody (palivizumab). An important question in HRSV pathogenesis research is why only a fraction (1 to 3%) of infants develop severe disease. Model systems comprising disease-relevant HRSV isolates and accurate and reproducible cell culture models are indispensable to study infection, replication, and innate immune responses. Here, we used differentiated AOs cultured at ALI to model the human airways. Subgroup A viruses replicated better than subgroup B viruses, which we speculate fits with epidemiological findings that subgroup A viruses cause more severe disease in infants. By using AOs cultured at ALI, we present a highly relevant, robust, and reproducible model that allows for future studies into what drives severe HRSV disease.

Child health, infant formula funding and South African health professionals: Eliminating conflict of interest.

Letters by Van Niekerk and Khan on article by Lake et al. (Lake L, Kroon M, Sanders D, et al. Child health, infant formula funding and South African health professionals: Eliminating conflict of interest. S Afr Med J 2019;109(12):902-906. https://doi.org/10.7196/SAMJ.2019.v109i12.14336); and response by Lake et al.

The prevalence of mental health problems in sub-Saharan adolescents living with HIV: a systematic review.

Despite the progress made in HIV treatment and prevention, HIV remains a major cause of adolescent morbidity and mortality in sub-Saharan Africa. As perinatally infected children increasingly survive into adulthood, the quality of life and mental health of this population has increased in importance. This review provides a synthesis of the prevalence of mental health problems in this population and explores associated factors. A systematic database search (Medline, PsycINFO, Scopus) with an additional hand search was conducted. Peer-reviewed studies on adolescents (aged 10-19), published between 2008 and 2019, assessing mental health symptoms or psychiatric disorders, either by standardized questionnaires or by diagnostic interviews, were included. The search identified 1461 articles, of which 301 were eligible for full-text analysis. Fourteen of these, concerning HIV-positive adolescents, met the inclusion criteria and were critically appraised. Mental health problems were highly prevalent among this group, with around 25% scoring positive for any psychiatric disorder and 30-50% showing emotional or behavioral difficulties or significant psychological distress. Associated factors found by regression analysis were older age, not being in school, impaired family functioning, HIV-related stigma and bullying, and poverty. Social support and parental competence were protective factors. Mental health problems among HIV-positive adolescents are highly prevalent and should be addressed as part of regular HIV care.

Child health, infant formula funding and South African health professionals: Eliminating conflict of interest.

Despite clear evidence of the benefits of exclusive and continued breastfeeding for children, women and society, far too few children in South Africa (SA) are breastfed. One of the major impediments to improving this situation is the continued and aggressive marketing of breastmilk substitutes (BMSs) and infiltration of the BMS industry into contexts with exposure to health professionals. In this article we, as academics, practitioners and child health advocates, describe contraventions of the regulations that protect breastfeeding in SA and argue that bold, proactive leadership to eliminate conflict of interest in respect of the BMS industry is urgently required, together with far greater investments in proven interventions to promote and support breastfeeding.

Selenium and large artery structure and function: a 10-year prospective study.

PURPOSE: Despite selenium's beneficial effects in counteracting oxidative stress, inflammation, and vascular endothelial dysfunction, controversial results exist regarding the long-term associations between selenium and atherosclerosis, arterial stiffness, and hypertension. We investigated in normal and selenium-deficient groups (and the total group), whether serum selenium relates to measures of large artery structure and function over 10 years. METHODS: This longitudinal study included black adults from rural and urban areas in South Africa. Serum selenium and blood pressure were measured at baseline (N = 987). At follow-up, carotid intima media thickness (IMT), cross-sectional wall area (CSWA), carotid-femoral pulse wave velocity (c-fPWV), and blood pressure were measured (N = 718). Selenium deficiency was classified as serum levels < 8 µg/100 ml. RESULTS: In multivariable-adjusted regression analyses performed in the normal selenium group, c-fPWV after 10 years was negatively associated with baseline selenium (ß = - 0.09; p = 0.016). In the normal selenium group, baseline (but not 10 years) blood pressure also associated negatively with baseline selenium (ß = - 0.09; p = 0.007). Both IMT (ß = 0.12; p = 0.001) and CSWA (ß = 0.10; p = 0.003) after 10 years associated positively with baseline selenium in the total, normal, and selenium-deficient groups. CONCLUSION: We found a long-term vascular protective association of selenium on arterial stiffness and blood pressure in Africans with normal selenium levels, supporting the notion that selenium fulfills a vascular protective role. In contrast, we found a potential detrimental association between selenium and carotid wall thickness, particularly evident in individuals within the highest quartile of serum selenium.

Interferon-Induced Transmembrane Protein 1 Restricts Replication of Viruses That Enter Cells via the Plasma Membrane.

The acute antiviral response is mediated by a family of interferon-stimulated genes (ISGs), providing cell-intrinsic immunity. Mutations in genes encoding these proteins are often associated with increased susceptibility to viral infections. One family of ISGs with antiviral function is the interferon-inducible transmembrane proteins (IFITMs), of which IFITM3 has been studied extensively. In contrast, IFITM1 has not been studied in detail. Since IFITM1 can localize to the plasma membrane, we investigated its function with a range of enveloped viruses thought to infect cells by fusion with the plasma membrane. Overexpression of IFITM1 prevented infection by a number of Paramyxoviridae and Pneumoviridae, including respiratory syncytial virus (RSV), mumps virus, and human metapneumovirus (HMPV). IFITM1 also restricted infection with an enveloped DNA virus that can enter via the plasma membrane, herpes simplex virus 1 (HSV-1). To test the importance of plasma membrane localization for IFITM1 function, we identified blocks of amino acids in the conserved intracellular loop (CIL) domain that altered the subcellular localization of the protein and reduced antiviral activity. By screening reported data sets, 12 rare nonsynonymous single nucleotide polymorphisms (SNPs) were identified in human IFITM1, some of which are in the CIL domain. Using an Ifitm1-/- mouse, we show that RSV infection was more severe, thereby extending the range of viruses restricted in vivo by IFITM proteins and suggesting overall that IFITM1 is broadly antiviral and that this antiviral function is associated with cell surface localization.IMPORTANCE Host susceptibility to viral infection is multifactorial, but early control of viruses not previously encountered is predominantly mediated by the interferon-stimulated gene (ISG) family. There are upwards of 300 of these genes, the majority of which do not have a clearly defined function or mechanism of action. The cellular location of these proteins may have an important effect on their function. One ISG located at the plasma membrane is interferon-inducible transmembrane protein 1 (IFITM1). Here we demonstrate that IFITM1 can inhibit infection with a range of viruses that enter via the plasma membrane. Mutant IFITM1 proteins that were unable to localize to the plasma membrane did not restrict viral infection. We also observed for the first time that IFITM1 plays a role in vivo, and Ifitm1-/- mice were more susceptible to viral lung infection. These data contribute to our understanding of how ISGs prevent viral infections.

Serum selenium levels, the selenoprotein glutathione peroxidase and vascular protection: The SABPA study.

Selenium is an important co-factor for the optimal functioning of the antioxidant enzyme, glutathione peroxidase (GPx). Studies investigating the associations of selenium with blood pressure (BP) and hemodynamic measures are sparse. This study investigated whether 24h blood pressure, vascular resistance, arterial compliance and arterial stiffness relate to both serum selenium and GPx activity. In this cross-sectional study selenium levels, GPx activity, ambulatory blood pressure and arterial stiffness of 200 black and 209 white school teachers from South Africa were measured. Serum selenium levels were significantly lower in black compared to white teachers (p<0.001), independent of sex. One in 10 black men and one in five black women were selenium deficient (<8µg/100ml). Only in white men inverse independent associations of 24h systolic BP (ß=-0.19; p=0.039) and 24h diastolic BP (ß=-0.21; p=0.029) with selenium were found. In the same group, an inverse association between carotid-dorsalis pedis pulse wave velocity (cd-PWV) and GPx activity (ß=-0.23; p=0.017) were also found. To conclude, lower serum selenium levels in black populations from the same geographical region as their white counterparts may impact on the loss of the vasculoprotective effects of selenium and selenoproteins such as GPx.

Stopped-flow kinetics of pH-responsive polyamine latexes: how fast is the latex-to-microgel transition?

Four poly(ethylene glycol)-stabilized polyamine latexes, namely, poly(2-vinylpyridine) (P2VP), poly(2-(tert-butylamino)ethyl methacrylate) (PTBAEMA), poly(2-(diethylamino)ethyl methacrylate) (PDEA), and poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) were prepared via emulsion copolymerization using divinylbenzene (DVB) as a cross-linker at 0.80 mol % for all formulations. According to dynamic light scattering studies, the resulting latexes were near-monodisperse and had approximately constant hydrodynamic diameters of 205-220 nm at pH 10; a latex-to-microgel transition was observed at around the respective pKa of each polyamine on addition of acid. The kinetics of swelling of each latex was investigated by the pH-jump method using a commercial stopped-flow instrument. The most rapid swelling was observed for the P2VP latex, which exhibited a characteristic swelling time (t*) of 5 ms. The corresponding t* values for PTBAEMA and PDEA were 25 and 35 ms, respectively, whereas the PDPA particles exhibited significantly slower swelling kinetics (t* = 180 ms). These t* values could not be correlated with either the latex Tg or the polyamine pKa. However, there is a positive correlation between t* and the repeat unit mass of the amine monomer, which suggests that the cationic charge density of the protonated polymer chains may influence the kinetics of swelling. Alternatively, the observed differences in swelling kinetics may simply reflect subtle differences in the DVB cross-link density, with more uniformly cross-linked latexes being capable of responding more quickly to a pH jump. The kinetics of deswelling for the corresponding microgel-to-latex transition was also briefly investigated for the PTBAEMA and P2VP particles. In both cases, much slower rates of deswelling were observed. This suggests that a latexlike "skin" is formed on the outer surface of the microgel particles during their deprotonation, which significantly retards the excretion of both salt and water.

[Thrombocytopenia during pregnancy]. / Trombocytopenie tijdens de zwangerschap.

Thrombocytopenia during pregnancy can be caused by a broad variety of disorders. An early diagnosis is essential for timely and adequate therapy. In cases of severe thrombocytopenia, a multidisciplinary approach by a team of obstetricians, haematologists and anaesthesiologists is needed. We describe a 30-year-old patient at a gestational age of 35 weeks who presented with preterm rupture of membranes. Coincidentally, she also had severe thrombocytopenia that proved to be due to immune thrombocytopenia (ITP). The severe thrombocytopenia persisted despite standard first-line treatment with corticosteroids and intravenous immunoglobulins. Based on this case report we discuss the differential diagnosis of thrombocytopenia during pregnancy with a focus on the management of ITP in pregnant women.

Novel Pickering emulsifiers based on pH-responsive poly(2-(diethylamino)ethyl methacrylate) latexes.

The emulsion copolymerization of 2-(diethylamino)ethyl methacrylate (DEA) with a divinylbenzene cross-linker in the presence of monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA) at 70 °C afforded near-monodisperse, sterically stabilized PEGMA-PDEA latexes at 10% solids. Dynamic light scattering studies indicated intensity-average diameters of 190 to 240 nm for these latexes at pH 9. A latex-to-microgel transition occurred on lowering the solution pH to below the latex pKa of 6.9. When dilute HCl/KOH was used to adjust the aqueous pH, a systematic reduction in the cationic microgel hydrodynamic diameter of 80 nm was observed over ten pH cycles as a result of the gradual buildup of background salt. However, no such size reduction was observed when using CO2/N2 gases to regulate the aqueous pH because this protocol does not generate background salt. Thus, the latter approach offers better reversibility, albeit at the cost of slower response times. PEGMA-PDEA microgel does not stabilize Pickering emulsions when homogenized at pH 3 with n-dodecane, sunflower oil, isononyl isononanoate, or isopropyl myristate. In contrast, PEGMA-PDEA latex proved to be a ubiquitous Pickering emulsifier at pH 10, forming stable oil-in-water emulsions with each of these four model oils. Lowering the solution pH from 10 to 3 resulted in demulsification within seconds. This is because these pH-responsive particles undergo a latex-to-microgel transition, which leads to their interfacial desorption. Six successive demulsification/emulsification cycles were performed on these Pickering emulsions using HCl/KOH to adjust the solution pH. Demulsification could also be achieved by purging the emulsion solution with CO2 gas to lower the aqueous pH to 4.8. However, complete phase separation required CO2 purging for 4 h at 20 °C. A subsequent N2 purge raised the aqueous pH sufficiently to induce a microgel-to-latex transition, but rehomogenization did not produce a stable Pickering emulsion. Presumably, a higher pH is required, which cannot be achieved by a N2 purge alone.

Effect of cottonseed oilcake inclusion on ostrich growth performance and meat chemical composition.

This study investigated the effect of replacing dietary soybean oilcake meal with increasing levels of cottonseed oilcake meal (CSOCM) on the growth performance and meat (Iliofibularis muscle) chemical composition of ostriches in order to decrease total feed costs. A total of 105 ostriches were divided into five feeding groups according to the CSOCM inclusion level in the whole diet: Control (0% CSOCM), 3%, 6%, 9% and 12% CSOCM (of the whole diet), and fed with experimental diets from 6 to 13 months of age. As a result of feeding CSOCM, the final live weight and the average daily gain significantly increased in the 12% CSOCM group. The proximate composition, cholesterol content, mineral and fatty acid profile of the meat remained unaffected. Thus CSOCM may be used as an alternative protein source to the more expensive soybean oilcake meal in ostrich nutrition.

Novel Pickering emulsifiers based on pH-responsive poly(tert-butylaminoethyl methacrylate) latexes.

Emulsion copolymerization of 2-(tert-butylamino)ethyl methacrylate in the presence of divinylbenzene (DVB) cross-linker and monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA) macromonomer at 70 °C afforded sterically-stabilized latexes at approximately 10% solids at pH 9. Dynamic light scattering and scanning electron microscopy (SEM) confirmed that relatively narrow size distributions were obtained. SEM confirmed the formation of spherical particles in the absence of any DVB cross-linker using a simple batch protocol, but in the presence of DVB it was necessary to use seeded emulsion polymerization under monomer-starved conditions to prevent the formation of latexes with ill-defined non-spherical morphologies. Lightly cross-linked latexes acquired cationic microgel character upon lowering the solution pH due to protonation of the secondary amine groups. Increasing the degree of cross-linking led to a progressively lower effective pK(a) of the copolymer chains from 8.0 to 7.3, which implies a gradual reduction in their basicity. Poly(tert-butylamino)ethyl methacrylate latex proved to be an effective Pickering emulsifier at pH 10, forming stable oil-in-water emulsions when homogenized with either n-dodecane or sunflower oil at 12,000 rpm for 2 min. These Pickering emulsions exhibited pH-responsive behavior: lowering the solution pH to 3 resulted in immediate demulsification due to the spontaneous desorption of the cationic microgels from the oil/water interface. Following rehomogenization at high pH, four successive demulsification/emulsification pH cycles could be achieved without a discernible loss in performance. However, no demulsification occurred on acidification of the fifth cycle, due to the progressive build-up of background salt.

Recombinant canine distemper virus strain Snyder Hill expressing green or red fluorescent proteins causes meningoencephalitis in the ferret.

The propensity of canine distemper virus (CDV) to spread to the central nervous system is one of the primary features of distemper. Therefore, we developed a reverse genetics system based on the neurovirulent Snyder Hill (SH) strain of CDV (CDV(SH)) and show that this virus rapidly circumvents the blood-brain and blood-cerebrospinal fluid (CSF) barriers to spread into the subarachnoid space to induce dramatic viral meningoencephalitis. The use of recombinant CDV(SH) (rCDV(SH)) expressing enhanced green fluorescent protein (EGFP) or red fluorescent protein (dTomato) facilitated the sensitive pathological assessment of routes of virus spread in vivo. Infection of ferrets with these viruses led to the full spectrum of clinical signs typically associated with distemper in dogs during a rapid, fatal disease course of approximately 2 weeks. Comparison with the ferret-adapted CDV(5804P) and the prototypic wild-type CDV(R252) showed that hematogenous infection of the choroid plexus is not a significant route of virus spread into the CSF. Instead, viral spread into the subarachnoid space in rCDV(SH)-infected animals was triggered by infection of vascular endothelial cells and the hematogenous spread of virus-infected leukocytes from meningeal blood vessels into the subarachnoid space. This resulted in widespread infection of cells of the pia and arachnoid mater of the leptomeninges over large areas of the cerebral hemispheres. The ability to sensitively assess the in vivo spread of a neurovirulent strain of CDV provides a novel model system to study the mechanisms of virus spread into the CSF and the pathogenesis of acute viral meningitis.

Streptococcus pneumoniae exposure is associated with human metapneumovirus seroconversion and increased susceptibility to in vitro HMPV infection.

It remains largely unknown which factors determine the clinical outcome of human metapneumovirus (HMPV) infections. The aim of the present study was to analyse whether exposure to bacterial pathogens can influence HMPV infections. From 57 children, serum samples and colonization data for Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Streptococcus pneumoniae were collected at 1.5, 6, 14 and 24 months of age. Seroconversion rates to HMPV were determined and related to bacterial carriage. Frequent nasopharyngeal carriage (≥2 times in the first 2 years of life) of S. pneumoniae, but not of the other three pathogens, was associated with increased seroconversion rates of infants to HMPV at the age of 2 years (frequently vs. less exposed, 93% vs. 59%; p <0.05). Subsequently, the susceptibility of well-differentiated normal human bronchial epithelial cells (wd-NHBE) pre-incubated with bacterial pathogens to in vitro HMPV infection was evaluated. Pre-incubation of wd-NHBE with S. pneumoniae resulted in increased susceptibility to infection with HMPV-enhanced green fluorescent protein (EGFP), as determined by enumeration of EGFP-positive cells. This was not the case for cells pre-incubated with H. influenzae, M. catarrhalis on S. aureus. We conclude that exposure to S. pneumoniae can modulate HMPV infection.

Feasibility study of three-nerve-recognizing Lichtenstein procedure for inguinal hernia.

BACKGROUND: Inguinal nerve identification during open inguinal hernia repair is associated with less chronic postoperative pain. However, most Dutch surgeons do not identify all three inguinal nerves when carrying out this procedure. The aim of this study was to evaluate the feasibility of a nerve-recognizing Lichtenstein hernia repair and to measure the extra time required for surgery METHODS: Forty patients with primary inguinal hernia were operated on following the nerve-recognizing Lichtenstein hernia repair by four experienced hernia surgeons from four different Dutch teaching hospitals. The additional time needed to identify each individual nerve was recorded, and iatrogenic nerve injuries and anatomical characteristics were registered. RESULTS: Identification of the iliohypogastric and ilioinguinal nerves was each performed within 1 min. Identification of the genital branch of the genitofemoral nerve was notably more difficult but could usually be performed within 2 min. Identification of the cremasteric vein, running parallel to the genital branch, was less comprehensive. The incidence of major anatomical variations was low. Twenty-five per cent of ilioinguinal nerves, however, could not be identified. In five patients inguinal nerves were damaged iatrogenically during standard manoeuvres of the Lichtenstein hernia repair. CONCLUSION: Three-nerve-recognizing Lichtenstein hernia repair is feasible and non-time consuming if the surgeon has appropriate anatomical knowledge. In view of the low incidence of major anatomical variations, knowledge of standard inguinal nervous anatomy should be adequate. This procedure could enable the surgeon to prevent or recognize iatrogenic nerve damage and offer an opportunity to perform deliberate neurectomy as an alternative to accidental nerve injury.

Measles studies in the macaque model.

Much of our current understanding of measles has come from experiments in non-human primates. In 1911, Goldberger and Anderson showed that macaques inoculated with filtered secretions from measles patients developed measles, thus demonstrating that the causative agent of this disease was a virus. Since then, different monkey species have been used for experimental measles virus infections. Moreover, infection studies in macaques demonstrated that serial passage of the virus in vivo and in vitro resulted in virus attenuation, providing the basis for all current live-attenuated measles vaccines. This chapter will review the macaque model for measles, with a focus on vaccination and immunopathogenesis studies conducted over the last 15 years. In addition, recent data are highlighted demonstrating that the application of a recombinant measles virus strain expressing enhanced green fluorescent protein dramatically increased the sensitivity of virus detection, both in living and sacrificed animals, allowing new approaches to old questions on measles vaccination and pathogenesis.

[Orthodontics in general practice 4. Impaction of maxillary front teeth]. / Orthodontie in de algemene tandartspraktijk 4. Eruptieproblemen in het bovenfront.

Eruption failures in the maxillary frontal region occur during the mixed dentition period. Dislocation and impaction of central incisors are diagnosed during or at the end of the early mixed dentition stage. These failures can be caused by crowding, premature loss of deciduous teeth, trauma or supernumerary teeth. Occasionally, a preventive orthodontic treatment is desirable to release the obstructed eruption path of a canine. Sometimes, a surgical intervention may be indicated to expose an obstructed central incisor and to remove supernumerary teeth. Retention and impaction of canines are generally discovered late in or after the late mixed dentition stage. In the agenesis of the lateral incisors or peg-shaped teeth, there is frequently impaction of the canines. General dental practitioners must be alert for possible deviations in the pattern of change in dentition right from the early mixed dentition period. Conventional two-dimensional radiographs can sometimes unjustifiably suggest a bad prognosis of an impacted tooth. Cone-beam CT scanning, which gives a three-dimensional image, can provide important additional diagnostic information.

[Orthodontics in general practice. 2. Treatment of eruption failures]. / Orthodontie in de algemene tandartspraktijk. 2. Behandeling van eruptieproblemen.

Since the introduction of composites and bonding in orthodontics, the possibilities of aligning impacted teeth into the dental arch after a surgical intervention, have remarkably increased. There are 4 important treatment techniques. The closed-eruption technique includes bracket-bonding to and ligating of the exposed tooth, followed by repositioning of the mucosal flap. The disadvantage of the method is the uncontrollable orthodontic force on the non-visible tooth during orthodontic extrusion. The open-eruption technique aims at keeping the exposed tooth visible, followed by spontaneous eruption. However, the exposure appears often as a radical exposure with unfavourable gingival consequences. The open-eruption technique with apical positioned mucosal flap is designed to expose teeth highly buccally impacted. The mucosal graft may cause a typical thick, stretched and not aesthetically acceptable gum after orthodontic treatment, even in case of using a split-thickness graft. The modified window technique is an open-eruption technique with minimal exposure, resulting in immediate eruption. If orthodontic treatment is required, the tooth is no longer impacted. The success rates of the 4 techniques vary from 75 until 99%. Study of the literature reveals insufficient scientific evidence in favour of 1 treatment technique. However, independent of the surgical technique applied, general practitioners play a crucial role in diagnostics of eruption failures and timely referral to an orthodontist.