Postrhinoplasty nasal cysts and the use of petroleum-based ointments and nasal packing

Nasal cysts are rare complications of rhinoplasty, and numerous theories exist regarding their cause. The term "paraffinoma" has been used to describe cyst formation observed after topical antibiotic ointment application with nasal packing in the immediate postoperative period. Such complications are rare but may occur because of the inherent properties of the agent used or a lack of meticulous technique (in the placement of incisions and nasal packing). Three cases of postrhinoplasty cysts with a variety of presentations, including incidental intraoperative findings, bilateral medial canthal masses, and a draining dorsal cyst, are described. Although such cysts are uncommon, techniques to prevent these unwanted sequelae should routinely be used, with the judicious application of non-petroleum-based topical antibiotic preparations.     

Processing of hierarchic stimulus structures has advantages in humans and animals

Carmesin and Schwegler (1994) have determined theoretically that a linear hierarchical stimulus structure can be encoded by a parallel network of minimal complexity. The experiments reported here compare the efficiency with which humans and pigeons process sets of stimulus pairs embodying different inequality structures. Groups of subjects of each species were taught to discriminate all 10 pairwise combinations of 5 stimuli with an operant conditioning method. For one group, the reward/punishment allocations within the pairs agreed with a linear hierarchy. For a second and third group, the reinforcement allocations of one or three, respectively, of the stimulus pairs deviated from such ordering. The time it took the subjects to learn the tasks as well as the final choice latencies and/or error rates increased with the number of deviating inequalities. The results agree with the assumption that both humans and pigeons encode stimulus inequality structures with parallel processing neural networks rather than with a sequentially processing algorithm.     

Alpha-synuclein has a high affinity for packing defects in a bilayer membrane: a thermodynamics study

A number of neurodegenerative disorders, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, are characterized by the intracellular deposition of fibrillar aggregates that contain a high proportion of alpha-synuclein (alphaS). The interaction with the membrane-water interface strongly modulates folding and aggregation of the protein. The present study investigates the lipid binding and the coil-helix transition of alphaS, using titration calorimetry, differential scanning calorimetry, and circular dichroism spectroscopy. Titration of the protein with small unilamellar vesicles composed of zwitterionic phospholipids below the chain melting temperature of the lipids yielded exceptionally large exothermic heat values. The sigmoidal titration curves were evaluated in terms of a simple model that assumes saturable binding sites at the vesicle surface. The cumulative heat release and the ellipticity were linearly correlated as a result of simultaneous binding and helix folding. There was no heat release and folding of alphaS in the presence of large unilamellar vesicles, indicating that a small radius of curvature is necessary for the alphaS-membrane interaction. The heat release and the negative heat capacity of the protein-vesicle interaction could not be attributed to the coil-helix transition of the protein alone. We speculate that binding and helix folding of alphaS depends on the presence of defect structures in the membrane-water interface, which in turn results in lipid ordering in the highly curved vesicular membranes. This will be discussed with regard to a possible role of the protein for the stabilization of synaptic vesicle membranes.     

Invasive Alternanthera philoxeroides has performance advantages over natives under flooding with high amount of nitrogen

Aquatic Ecology - Climate changes and artificial disturbance in riparian wetlands commonly increase the flooding and nitrogen enrichment in those zones. Functional traits were considered as a...     

Rabbit nasal cytochrome P-450 NMa has high activity as a nicotine oxidase

Rabbit nasal olfactory and respiratory microsomes demonstrate high activity toward [3H]-(S)-nicotine, with specific activities of 22.2 and 6.5 nmol/min/mg protein, respectively. The major metabolite produced is (S)-nicotine delta 1'; 5'-iminium ion, with lesser amounts of nornicotine and the N'-oxide. Reconstitution of the rabbit nasal microsomal system with cytochromes P-450 NMa and NMb indicated that only P-450 NMa has significant activity toward nicotine, and the metabolite profile and turnover are similar to that observed with nasal microsomes. The low Km (35 microMs) and high Vmax (28 min-1) suggest that a significant portion of inhaled nicotine is metabolized by nasal tissues in the rabbit.     

Molecular packing and packing defects in helical membrane proteins

The packing of helices spanning lipid bilayers is crucial for the stability and function of alpha-helical membrane proteins. Using a modified Voronoi procedure, we calculated packing densities for helix-helix contacts in membrane spanning domains. Our results show that the transmembrane helices of protein channels and transporters are significantly more loosely packed compared with helices in globular proteins. The observed packing deficiencies of these membrane proteins are also reflected by a higher amount of cavities at functionally important sites. The cavities positioned along the gated pores of membrane channels and transporters are noticeably lined by polar amino acids that should be exposed to the aqueous medium when the protein is in the open state. In contrast, nonpolar amino acids surround the cavities in those protein regions where large rearrangements are supposed to take place, as near the hinge regions of transporters or at restriction sites of protein channels. We presume that the observed deficiencies of helix-helix packing are essential for the helical mobility that sustains the function of many membrane protein channels and transporters.     

Vertically transmitted symbionts in structured host metapopulations

We develop a structured metapopulation model for vertically transmitted symbionts in natural host populations. We focus primarily on two questions: Are mutualism and high transmission probability prerequisites for the survival of symbionts in structured host metapopulations? What are the ecological conditions under which coexistence of infected and uninfected hosts is possible? We start with studying in depth the case of qualitatively identical patches and derive conditions for invasion and coexistence of uninfected and infected hosts. Our model predicts that, in a qualitatively uniform environment, coexistence is possible only if the symbionts increase the fitness of their host, so the mutualism is indeed needed for coexistence. We also prove that evolution selects for 100% infection frequency in the metapopulation. Then we generalize the model for different patch qualities and get conditions for invasion in a virgin environment.     

Odorant binding protein has the biochemical properties of a scavenger for 4-hydroxy-2-nonenal in mammalian nasal mucosa

Odorant binding proteins (OBP) are soluble lipocalins produced in large amounts in the nasal mucosa of several mammalian species. Although OBPs can bind a large variety of odorous compounds, direct and exclusive involvement of these proteins in olfactory perception has not been clearly demonstrated. This study investigated the binding properties and chemical resistance of OBP to the chemically reactive lipid peroxidation end-product 4-hydroxy-2-nonenal (HNE), in an attempt to establish a functional relationship between this protein and the molecular mechanisms combating free radical cellular damage. Experiments were carried out on recombinant porcine and bovine OBPs and results showed that both forms were able to bind HNE with affinities comparable with those of typical OBP ligands (K(d) = 4.9 and 9.0 microm for porcine and bovine OBP, respectively). Furthermore, OBP functionality, as determined by measuring the binding of the fluorescent ligand 1-aminoanthracene, was partially lost only when incubating HNE levels and exposure time to HNE exceeded physiological values in nasal mucosa. Finally, preliminary experiments in a simplified model resembling nasal epithelium showed that extracellular OBP can preserve the viability of an epithelial cell line derived from bovine turbinates exposed to toxic amounts of the aldehyde. These results suggest that OBP, which is expressed at millimolar levels, might reduce HNE toxicity by removing from the nasal mucus a significant fraction of the aldehyde that is produced as a consequence of direct exposure to the oxygen present in inhaled air.     

Vertically transmitted HIV infection in the British Isles.

OBJECTIVE--To describe the epidemiology of vertically acquired HIV infection in the British Isles, the level of underreporting, the vertical transmission rate, and clinical spectrum of paediatric AIDS. DESIGN--Confidential, linked registers based on reporting from obstetricians and paediatricians; anonymous unlinked neonatal HIV serosurveys. SETTING--British Isles. SUBJECTS--Children born to mothers with HIV infection. MAIN OUTCOME MEASURES--Trends in HIV infection and vertical transmission rate. RESULTS--In Scotland and the Irish Republic, where most maternal HIV infection is related to drug misuse, the annual number of reports of children born to infected mothers has fallen since 1989. In England and Wales nearly half of maternal infections have been acquired overseas, and the number of children born to these women, and to women who became infected in Britain, is increasing. In south east England the proportion of live births to women whose infection was identified before delivery was only 17% (50/287), compared with 68% (26/38) in Scotland. The vertical transmission rate was 13.7% (23/168), and 23% of infected children developed AIDS in the first year of life. 41% (38/92) of children born to infected mothers who were ascertained after delivery were breast fed, compared with 5% (12/236) of those ascertained before delivery. CONCLUSIONS--The incidence of vertically transmitted HIV infection is increasing in England and Wales. More extensive antenatal testing would enable infected women to be counselled against breast feeding, which could prevent a substantial proportion of vertical transmission in some areas, and would increase opportunities for early diagnosis and treatment of infected children.     

Non-Mendelian transmission in a human developmental disorder: split hand/split foot.

The study of Mendelian disorders that do not meet some Mendelian expectations has led to an increased understanding of such previously obscure genetic phenomena as anticipation. Split hand/split foot (SHSF), a human developmental malformation, demonstrates such distinctive genetic features as reduced penetrance and variable expressivity. In this study, new pedigrees with defined ascertainment confirm the existence of non-Mendelian transmission characterized by the overtransmission of SHSF from affected fathers to sons.     

Genome Erosion in a Nitrogen-Fixing Vertically Transmitted Endosymbiotic Multicellular Cyanobacterium

Background

An ancient cyanobacterial incorporation into a eukaryotic organism led to the evolution of plastids (chloroplasts) and subsequently to the origin of the plant kingdom. The underlying mechanism and the identities of the partners in this monophyletic event remain elusive.

Methodology/Principal Findings

To shed light on this evolutionary process, we sequenced the genome of a cyanobacterium residing extracellularly in an endosymbiosis with a plant, the water-fern Azolla filiculoides Lam. This symbiosis was selected as it has characters which make it unique among extant cyanobacterial plant symbioses: the cyanobacterium lacks autonomous growth and is vertically transmitted between plant generations. Our results reveal features of evolutionary significance. The genome is in an eroding state, evidenced by a large proportion of pseudogenes (31.2%) and a high frequency of transposable elements (∼600) scattered throughout the genome. Pseudogenization is found in genes such as the replication initiator dnaA and DNA repair genes, considered essential to free-living cyanobacteria. For some functional categories of genes pseudogenes are more prevalent than functional genes. Loss of function is apparent even within the ‘core’ gene categories of bacteria, such as genes involved in glycolysis and nutrient uptake. In contrast, serving as a critical source of nitrogen for the host, genes related to metabolic processes such as cell differentiation and nitrogen-fixation are well preserved.

Conclusions/Significance

This is the first finding of genome degradation in a plant symbiont and phenotypically complex cyanobacterium and one of only a few extracellular endosymbionts described showing signs of reductive genome evolution. Our findings suggest an ongoing selective streamlining of this cyanobacterial genome which has resulted in an organism devoted to nitrogen fixation and devoid of autonomous growth. The cyanobacterial symbiont of Azolla can thus be considered at the initial phase of a transition from free-living organism to a nitrogen-fixing plant entity, a transition process which may mimic what drove the evolution of chloroplasts from a cyanobacterial ancestor.     

Evidence for locus heterogeneity in human autosomal dominant split hand/split foot malformation.

Split hand/split foot (SHSF; also known as ectrodactyly) is a human developmental disorder characterized by missing central digits and other distal limb malformations. An association between SHSF and cytogenetically visible rearrangements of chromosome 7 at bands q21-q22 provides compelling evidence for the location of a causative gene at this location, and the locus has been designated SHFD1. In the present study, marker loci were localized to the SHFD1 critical region through the analysis of somatic cell hybrids derived from individuals with SHSF and cytogenetic abnormalities involving the 7q21-q22 region. Combined genetic and physical data suggest that the order of markers in the SHFD1 critical region is cen-D7S492-D7S527-(D7S479-D7S491)-SHFD1-++ +D7S554-D7S518-qter. Dinucleotide repeat polymorphisms at three of these loci were used to test for linkage of SHSF to this region in a large pedigree that demonstrates autosomal dominant SHSF. Evidence against linkage of the SHSF gene to 7q21-q22 was obtained in this pedigree. Therefore, combined molecular and genetic data provide evidence for locus heterogeneity in autosomal dominant SHSF. We propose the name SHSF2 for this second locus.     

Fibrinolytic components in nasal mucosa and nasal secretion

 We evaluated a possible role for fibrinolytic components in nasal secretion by tissue localization with immunohistochemical techniques and by measuring their antigen concentrations in nasal discharge by means of ELISA and fibrin autography. Nasal mucosa was obtained surgically from the inferior turbinate. Urokinase-type plasminogen activator (u-PA) specific staining was observed in pseudostratified ciliated epithelium and was predominant in mucous cells of the seromucinous gland, while serous cells were almost devoid of stain. The pattern of staining of plasminogen activator inhibitor-2 was similar to that of u-PA. In contrast, plasminogen activator inhibitor-1(PAI-1) immunoreactive material was localized exclusively in serous cells of seromucinous glands. Positive staining for tissue-type plasminogen activator (t-PA) was observed in endothelial cells and basal cells, which differentiate into either ciliated or goblet cells. Nasal secretions were partially fractionated by immunospecific antibody-immobilized Sepharose. Subsequent fibrin autography patterns indicated the presence of u-PA, PAI-1, and t-PA. After methacholine provocation, the level of t-PA increased transiently but decreased rapidly with subsequent challenges. These differential stainings of fibrinolytic components and the existence of PAs and PAI-1 in the nasal discharge suggest that the fibrinolytic system may play a role in the movement and fluidity of nasal secretion. Accepted: 25 May 1998     

Nucleosome packing in interphase chromatin.

Higher-order chromatin fibers (200--300 A in diameter) are reproducibly released from nuclei after lysis in the absence of formalin and/or detergent. Electron microscope analysis of these fibers shows that they are composed of a continuous array of closely apposed nucleosomes which display several distinct packing patterns. Analysis of the organization of nucleosomes within these arrays and their distribution along long stretches of chromatin suggest that the basic 100-A chromatin fiber is not packed into discrete superbeads and is not folded into a uniform solenoid within the native 250-A fiber. Furthermore, because similar higher-order fibers have been visualized in metaphase chromosomes, the existence of this fiber class appears to be independent of the degree of in vivo chromatin condensation.     

Excluded volume in protein side-chain packing

The excluded volume occupied by protein side-chains and the requirement of high packing density in the protein interior should severely limit the number of side-chain conformations compatible with a given native backbone. To examine the relationship between side-chain geometry and side-chain packing, we use an all-atom Monte Carlo simulation to sample the large space of side-chain conformations. We study three models of excluded volume and use umbrella sampling to effectively explore the entire space. We find that while excluded volume constraints reduce the size of conformational space by many orders of magnitude, the number of allowed conformations is still large. An average repacked conformation has 20 % of its chi angles in a non-native state, a marked reduction from the expected 67 % in the absence of excluded volume. Interestingly, well-packed conformations with up to 50 % non-native chi angles exist. The repacked conformations have native packing density as measured by a standard Voronoi procedure. Entropy is distributed non-uniformly over positions, and we partially explain the observed distribution using rotamer probabilities derived from the Protein Data Bank database. In several cases, native rotamers that occur infrequently in the database are seen with high probability in our simulation, indicating that sequence-specific excluded volume interactions can stabilize rotamers that are rare for a given backbone. In spite of our finding that 65 % of the native rotamers and 85 % of chi(1) angles can be predicted correctly on the basis of excluded volume only, 95 % of positions can accommodate more than one rotamer in simulation. We estimate that, in order to quench the side-chain entropy observed in the presence of excluded volume interactions, other interactions (hydrophobic, polar, electrostatic) must provide an additional stabilization of at least 0.6 kT per residue in order to single out the native state.