Human papillomavirus infection and cervical intraepithelial neoplasia in women with renal allografts.

An increased prevalence of cervical cancer has been observed in immunosuppressed women, but controlled studies are rare. Biopsy specimens from 49 women with renal allografts and 69 non-immunosuppressed controls (with no history of cervical intraepithelial neoplasia, vulval warts, or abnormal results of cervical smear tests) were assessed for colposcopic appearance, cytological and histological diagnosis, and the presence of human papillomavirus types 6/11 and 16/18 DNA sequences. At colposcopy 26 (53%) of the women with allografts had cervical abnormalities compared with 20 (29%) of the controls. The prevalence of cervical intraepithelial neoplasia was significantly higher in the women with allografts (24 (49%) compared with 7 (10%]. The overall rate of detection of human papillomavirus DNA did not differ significantly between the two groups. There was however, a significant difference in the rate of detection of human papillomavirus type 16/18 DNA (27% in the women with allografts and 6% in the controls). These data confirm that pathological and virological changes affecting the cervix are significantly increased in immunosuppressed women and emphasise the need for regular colposcopic examination.     

Localization of sequences regulating ancestral and acquired sites of esterase6 activity in Drosophila melanogaster

We have broadly defined the DNA regions regulating esterase6 activity in several life stages and tissue types of D. melanogaster using P- element-mediated transformation of constructs that contain the esterase6 coding region and deletions or substitutions in 5' or 3' flanking DNA. Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and the primary sequences regulating its activity lie between -171 and -25 bp relative to the translation initiation site: deletion of these sequences decrease activity approximately 20-fold. Hemolymph activity is also modulated by four other DNA regions, three of which lie 5' and one of which lies 3' of the coding region. Of these, two have positive and two have negative effects, each of approximately twofold. Esterase6 activity is present also in two male reproductive tract tissues; the ejaculatory bulb, which is another ancestral activity site, and the ejaculatory duct, which is a recently acquired site within the melanogaster species subgroup. Activities in these tissues are at least in part independently regulated: activity in the ejaculatory bulb is conferred by sequences between -273 and -172 bp (threefold decrease when deleted), while activity in the ejaculatory duct is conferred by more distal sequences between -844 and -614 bp (fourfold decrease when deleted). The reproductive tract activity is further modulated by two additional DNA regions, one in 5' DNA (-613 to -284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to +2731 bp; threefold decrease when deleted) that probably overlaps the adjacent esteraseP gene. Collating these data with previous studies suggests that expression of EST6 in the ancestral sites is mainly regulated by conserved proximal sequences while more variable distal sequences regulate expression in the acquired ejaculatory duct site.      

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.      

Iron content correlates with peroxidase activity in cysteamine-induced astroglial organelles.

A subpopulation of astrocytes in periventricular brain regions and in cysteamine-treated neuroglial cultures contains cytoplasmic granules that exhibit an affinity for Gomori stains, orange-red autofluorescence, and non-enzymatic peroxidase activity. The autofluorescence and pseudoperoxidase activity are consistent with the presence of porphyrins and heme iron, respectively. In the present study, we employed diaminobenzidine cytochemistry, transmission electron microscopy, and energy-dispersive X-ray microanalysis (electron microprobe) in an attempt to correlate fine structure with the peroxidase activity and elemental composition of the cysteamine-induced inclusions in cultured astrocytes. In osmicated preparations, these membrane-bound inclusions varied greatly in size, were round or ovoid in shape, and exhibited an intensely electron-dense granular matrix. In non-osmicated preparations, many inclusions exhibited internal membranous partitions producing complex subcompartmentalization. Diaminobenzidine reaction product, indicative of endogenous peroxidase activity, was occasionally observed distributed diffusely throughout the granule matrix. More commonly, peroxidase activity was restricted to specific intraorganellar compartments. Elemental iron was detected in the inclusions by electron microprobe analysis. The presence and concentration of iron in these organelles correlated closely with the presence and intensity of diaminobenzidine staining, suggesting that redox-active iron mediates the pseudoperoxidase reactions in these cells. Cysteamine-induced derangements of porphyrin-heme biosynthesis may be responsible for the proliferation of iron-containing gliosomes in these astrocytes.     

Localization of phosphatases in Trypanosoma rhodesiense

Phosphatase activity in Trypanosoma rhodesiense has been examined histochemically by light and electron microscopy and by enzymatic assay in homogenate fractions. Using a method with lead as capture ion, acid phosphatase was found in lysosome-like vesicles and in the flagellar pocket. No alkaline adenosine triphosphatase (ATPase) was detectable by this method. Direct assay of p-nitrophenylphosphatase activity in homogenate fractions showed that acid phosphatase activity was strongly membrane-bound, but that activity at pH 9 was minimal in both soluble and particulate fractions. "Endogenous" ATPase activity was localized specifically and reproducibly in the mitochondrial membranes and under the plasma membrane of he flagellum. This nonenzymic reaction product could not be eradicated by glycerol extraction or glucose depletion. Unlike the membrane staining, which was manifest only after lead treatment, heat-resistant electron-dense material was found in the matrix of lysosomal vesicles in trypanosomes fixed in glutaraldehyde only and not subjected to further treatment with heavy metal reagents. X-ray emission analysis showed the presence of calcium and phosphorus, indicating that the matrix might have a phosphate storage function.     

Tracking fatty acid kinetics in distinct lipoprotein fractions in vivo: a novel high-throughput approach for studying dyslipidemia in rodent models

Isotopic tracers have been used to examine lipid trafficking for many years, and data from those studies have typically yielded novel insight regarding the pathophysiology of dyslipidemia. Previous experimental designs were suitable for studies in humans because relatively large volumes of plasma could be regularly sampled. We have expanded on the earlier logic by applying high-throughput analytical methods that require reduced sample volumes. Specifically, we have examined the possibility of coupling gel-based separations of lipoproteins (e.g., lipoprint) with LC-MS/MS analyses of complex lipid mixtures as a way to routinely measure the labeling profiles of distinct lipids in discrete lipoprotein subfractions. We demonstrate the ability to measure the incorporation of [U-¹³C]oleate into triglycerides (TG), PLs (PL), and cholesterol esters (CE) in VLDL, LDL, and HDL particles in mice. Although rodent models of dyslipidemia are inherently different from humans because of alterations in enzyme activities and underlying metabolism, rodent models can be used to screen novel compounds for efficacy in altering a given biochemical pathway and therein enable studies of target engagement in vivo. We expect that it is possible to translate our approach for application in other systems, including studies in humans.     

The role of snail aestivation in transmission of schistosomiasis in changing climatic conditions

Schistosomiasis vector snails are subjected to extreme seasonal changes, particularly in ephemeral rivers and lentic waterbodies. In the tropics, aestivation is one of the adaptive strategies for survival and is used by snails in times of extremely high temperatures and desiccation. Aestivation therefore plays an important role in maintaining the transmission of schistosomiasis. This review assesses the possible impacts of climate change on the temporal and spatial distribution of schistosomiasis-transmitting snails with special emphasis on aestivation, and discusses the effect of schistosome infection on aestivation ability. The impacts of parasite development on snails, as well as physiological changes, are discussed with reference to schistosomiasis transmission. This review shows that schistosome-infected snails have lower survival rates during aestivation, and that those that survive manage to get rid of the infection. In general, snail aestivation ability is poor and survival chances diminish with time. Longer dry periods result in fewer, as well as uninfected, snails. However, the ability of the surviving snails to repopulate the habitats is high.     

Modeling Hurricane Exposure in a Caribbean Lower Montane Tropical Wet Forest: The Effects of Frequent,Intermediate Disturbances and Topography on Forest Structural Dynamics and Composition

Frequent intermediate disturbances can produce qualitatively different spatial heterogeneity and environmental variability than large infrequent disturbances, which facilitates the coexistence of disparate species types. We hypothesized that species coexistence will be maximized at sites exposed to recurring hurricanes with intermediate frequencies and effects. Consequently, we sought to determine if exposure vulnerability (EV) from three hurricanes with intermediate effects and frequencies (Ivan-2004, Dennis-2005 and Dean-2007), or the interaction between exposure and topography, could be used to explain forest structural dynamics and composition. We used data obtained in 2006 and 2012 from within 45, 25 × 25 m (2.8125 ha) permanent sample plots, established according to a randomized block design, and stratified according to elevation and aspect/sites (NE and SW facing ridges) in a tropical montane wet forest, John Crow Mountains, Jamaica. There was a significant reduction in basal area (BA) (14%), tree volume (10%), and density (26%) and there was a negative shift in the height profile of trees. Understory light (2008), stem density, and mortality increased with EV but decreased with aspect. The NE aspect/sites had higher EV after Dean and the other hurricanes. Consequently, BA, volume and density increased significantly for light-demanding species at the NE sites, but declined significantly overall with minimal changes at SW sites. Moreover, diversity was significantly higher at sites with higher EV for the three hurricanes. The frequent hurricanes with intermediate effects may have therefore maintained/increased spatial heterogeneity, which promoted the coexistence of species with disparate life histories at more exposed sites.