Phenotypic variability and therapeutic implications of Candida species in patients with oral lichen planus

We investigated the prevalence and phenotypic variation of Candida species in oral lichen planus (OLP) and the therapeutic implications of our findings. Eighty patients with clinically and histopathologically confirmed cases of OLP (64 non-erosive, 16 erosive) and a control group of 80 healthy individuals with no predisposing factors for oral candidiasis were examined for evidence of Candida infection. Oral swabs and smears were obtained for cytology and culture. Identification, speciation and antifungal susceptibility tests of Candida isolates were performed using an automated microbial identification system. Fifty percent of erosive OLP cases, 28% of non-erosive cases and none of the controls showed evidence of Candida. Candida albicans was found predominantly in non-erosive OLP, while other Candida species were predominate in erosive OLP. Non-Candida albicans isolates (C. glabrata, C. krusei) were resistant to the commonly used antifungals, clotrimazole and fluconazole. Candida infection is common in cases of OLP. We recommend antifungal sensitivity testing prior to antifungal therapy for the erosive form of OLP.     

Etude “in vitro” des acides gras synthétisés dans les microsomes de cerveaux de souris normales et “quaking”

Radiogas chromatographic studies of the products of fatty acid biosynthesis in mice brain microsomes confirm the existence of a «de novo system from acetyl-CoA and malonyl-CoA and of a least two elongating systems for long chain fatty acids, involving malonyl-CoA. The possibility of an intermediary system leading from C₁₈ to C₂₀ fatty acids has been evoked.Comparison between non mutant and quaking mice indicates that all the microsomal fatty acid biosynthetic systems are depressed. The biosynthetic system elongating fatty acids from C₁₈ is the one which is the most modified quantitatively and qualitatively in quaking. Microsomal and soluble «de novo systems are qualitatively intact.     

Estrogen-Induced Synthesis of Yolk Proteins in Roosters

Vitellogenin is the serum precursor of the yolk proteins -lipovitellin,rß-lipovitellin, and phosvitin. The precursor canbe dissociated to produce the yolk proteins only by proteolyticenzymatic action, to which it is very susceptible. Denaturationin sodium dodecyl sulfate, combined with reduction of disulfidebridges and blocking of thiols, yields a complex with a molecularweight of 200,000 to 250,000. -Lipovitellin contains three polypeptides,with molecular weights of about 135,000, 105,000, and 40,000,and rß-lipovitellin is composed of two polypeptidechains with molecular weights of 135,000 and 30,000. The 40,000subunit of -lipovitellin and both rß-lipovitellinsubunits are phosphopeptides We tested RNA isolated from the liver of estrogen-treated roostersfor mRNA activity in a cell-free reticulocyte system. The vitellogeninmRNA has a sedimentation coefficient greater than 28S and thuscontains enough information to code for a long polypeptide chain.Estrogen administration to roosters induces the appearance ofvitellogenin and a lowdensity lipoprotein, the syntheses ofwhich are not coordinated. The course of vitellogenin synthesiswas calculated from accumulation and turnover data, and it wasfound that from about 25 hr after estradiol-17rß administrationthe rate of vitellogenin synthesis increases linearly for severaldays, paralleling an increase in vitellogenin-synthesizing polysomes.Thus, we estimate a constant translation rate of about 8 aminoacids per ribosome per sec. A "memory" effect is observed when a second hormone dose isgiven some time after the vitellogenin induced by the firstdose has disappeared from the blood. After the second dose vitellogeninsynthesis is detected sooner, and its initial increase is morerapid, than after the first dose. Although the synthesis ofvitellogenin starts 3 to 4 hr after the second as well as afterthe first injection, the rate of synthesis after the first injectionincreases much more slowly during the first 15 hr than duringthe subsequent period of linear accumulation, whereas afterthe second injection the linear increase in the rate of synthesisbegins immediately after the lag period of 3 to 4 hr. The "memory"effect is undiminished even 50 days after the first hormonedose; thus, the causative factor either is very stable or issynthesized in great excess during the first stimulation. Whenthe second injection is given during the descending part ofthe turnover curve, an increase in vitellogenin synthesis isobserved within 3.5 hr. There are thus at least three different effects of estradiol;(i) the "memory" effect, which probably is due to commitmentor differentiation of vitellogenin-synthesizing cells; (ii)the effect that causes the committed cells to give full responseafter the 3- to 4-hr lag period; and (iii) the effect that causesthe immediate response. To explain these results we suggestthat committed cells can synthesize vitellogenin mRNA only duringa certain period of the cell cycle.     

Phosphatidylinositol is involved in the membrane attachment of NCAM-120, the smallest component of the neural cell adhesion molecule.

The rodent neural cell adhesion molecule (NCAM) consists of three glycoproteins with Mr of 180,000, 140,000 and 120,000. The Mr 120,000 protein (NCAM-120) has been shown to exist in membrane-bound and soluble forms but the nature of its membrane association and release has remained obscure. We show here that phosphatidylinositol-specific phospholipase C (PI-PLC), but not a phospholipase C of different specificity, releases a substantial proportion of NCAM-120 from brain membranes and solubilizes almost quantitatively NCAM-120 present at the surface of C6 astroglial cells. The PI-PLC effect was highly selective since only one other protein species was detectably released from C6 cells. These results suggest that NCAM-120 is held in the membrane by covalently bound phosphatidylinositol or a closely related lipid in a way similar to several other surface proteins from eukaryotic cells. The presence of NCAM in a form which can be released from the cell surface by a highly selective mechanism raises additional possibilities for modulation and control of cell--cell adhesion.     

Specific stimulation of ribosomal RNA synthesis in E. coli by a protein factor

Summary Ribosomal RNA synthesis in a purified system is stimulated by a crude protein fraction prepared from E. coli. The positive effector which is not associated with RNA polymerase, nor is the sigma factor, increases the initiation frequency on a rRNA operon. The additional rRNA synthesis is inhibited by ppGpp to the same extent as the basal one.The evidence presented points to the existence of a positive control element for rRNA synthesis, which activity depends upon the physiological state of the cell.     

Characterization of a polymorphism in the 3′ part of the chicken vitellogenin gene

Summary An allele giving rise to a polymorphism within the 3 part of the chicken vitellogenin gene was cloned, sequenced, and compared to the previously cloned allele. The polymorphism is formed by a perfect copy of 343 bp from intron 32 in tandem array with a perfect copy of 244 bp from intron 33; this 587-bp element is inserted in a head-to-tail arrangement in intron 33. We propose a mechanism in which an unequal crossing-over resulted in a vitellogenin gene with two exons 33, one of which was subsequently deleted. Thus, intron 33 was enlarged by the tandem repeats without affecting the protein-encoding sequence of the gene. At the boundaries of the repeated elements, two short direct repeats are found that resemble the recombination signals of immunoglobulin genes. They may have had a key role in the formation of the new allele.     

The high-resolution NMR structure of the R21A Spc-SH3:P41 complex: Understanding the determinants of binding affinity by comparison with Abl-SH3

Background  

SH3 domains are small protein modules of 60–85 amino acids that bind to short proline-rich sequences with moderate-to-low affinity and specificity. Interactions with SH3 domains play a crucial role in regulation of many cellular processes (some are related to cancer and AIDS) and have thus been interesting targets in drug design. The decapeptide APSYSPPPPP (p41) binds with relatively high affinity to the SH3 domain of the Abl tyrosine kinase (Abl-SH3), while it has a 100 times lower affinity for the α-spectrin SH3 domain (Spc-SH3).     

Sex-specific demographic behaviours that shape human genomic variation

In the human species, the two uniparental genetic systems (mitochondrial DNA and Y chromosome) exhibit contrasting diversity patterns. It has been proposed that sex-specific behaviours, and in particular differences in migration rate between men and women, may explain these differences. The availability of high-density genomic data and the comparison of genetic patterns on autosomal and sex chromosomes at global and local scales allow a reassessment of the extent to which sex-specific behaviours shape our genome. In this article, we first review studies comparing the genetic patterns at uniparental and biparental genetic systems and assess the extent to which sex-specific migration processes explain the differences between these genetic systems. We show that differences between male and female migration rates matter, but that they are certainly not the only contributing factor. In particular, differences in effective population size between men and women are also likely to account for these differences. Then, we present and discuss three anthropological processes that may explain sex-specific differences in effective population size and thus human genomic variation: (i) variance in reproductive success arising from, for example, polygyny; (ii) descent rules; and (iii) transmission of reproductive success.