Relationship between 24-hour urinary-free cortisol excretion and salivary cortisol levels sampled from awakening to bedtime in healthy subjects

The utility of repeated salivary cortisol sampling as a substitute for 24-hour urinary-free cortisol (UFC) assessment was examined. Forty-four participants completed both 24-hour collections and 6 salivary collections at wake-up, 08:00, 12:00, 16:00, 20:00 and bedtime, during the same 24-hour period. The results demonstrated that mean, maximum, and amplitude (maximum minus minimum) for salivary cortisol all correlated positively with urinary cortisol, but the associations of these variables with urinary-free cortisol excretion were relatively small. Furthermore, a single salivary sample taken at wake-up was as good an indicator of overall cortisol production as the measures derived from multiple salivary samples. An examination of subject compliance indicated that many subjects failed to collect the timed salivary collections as instructed. The authors conclude that diurnal salivary cortisol sampling versus 24-hour urinary cortisol collections are likely to provide different information about ambient hypothalamic-pituitary-adrenal productivity, and therefore these measures should not be used interchangeably. In addition, subject compliance is a serious consideration in designing studies that employ home salivary collections.     

Association mapping and marker-assisted selection of the lettuce dieback resistance gene Tvr1

Background  

Lettuce (Lactuca saliva L.) is susceptible to dieback, a soilborne disease caused by two viruses from the family Tombusviridae. Susceptibility to dieback is widespread in romaine and leaf-type lettuce, while modern iceberg cultivars are resistant to this disease. Resistance in iceberg cultivars is conferred by Tvr1 - a single, dominant gene that provides durable resistance. This study describes fine mapping of the resistance gene, analysis of nucleotide polymorphism and linkage disequilibrium in the Tvr1 region, and development of molecular markers for marker-assisted selection.     

Novel dual-function CellDetect® staining technology: wedding morphology and tinctorial discrimination to detect cervical neoplasia

Immunocompromised patients who develop invasive filamentous mycotic infections can be efficiently treated if rapid identification of the causative fungus is obtained. We report a case of fatal necrotic pneumonia caused by combined pulmonary invasive mucormycosis and aspergillosis in a 66 year-old renal transplant recipient. Aspergillus was first identified during the course of the disease by cytological examination and culture (A. fumigatus) of bronchoalveolar fluid. Hyphae of Mucorales (Rhizopus microsporus) were subsequently identified by culture of a tissue specimen taken from the left inferior pulmonary lobe, which was surgically resected two days before the patient died. Histological analysis of the lung parenchyma showed the association of two different filamentous mycoses for which the morphological features were evocative of aspergillosis and mucormycosis. However, the definitive identification of the associative infection was made by polymerase chain reaction (PCR) performed on deparaffinized tissue sections using specific primers for aspergillosis and mucormycosis. This case demonstrates that discrepancies between histological, cytological and mycological analyses can occur in cases of combined mycotic infection. In this regard, it shows that PCR on selected paraffin blocks is a very powerful method for making or confirming the association of different filamentous mycoses and that this method should be made available to pathology laboratories.     

Of mice and mammoths: generality and antiquity of the island rule

Aim

We assessed the generality of the island rule in a database comprising 1593 populations of insular mammals (439 species, including 63 species of fossil mammals), and tested whether observed patterns differed among taxonomic and functional groups.

Location

Islands world‐wide.

Methods

We measured museum specimens (fossil mammals) and reviewed the literature to compile a database of insular animal body size (S_i = mean mass of individuals from an insular population divided by that of individuals from an ancestral or mainland population, M). We used linear regressions to investigate the relationship between S_i and M, and ANCOVA to compare trends among taxonomic and functional groups.

Results

S_i was significantly and negatively related to the mass of the ancestral or mainland population across all mammals and within all orders of extant mammals analysed, and across palaeo‐insular (considered separately) mammals as well. Insular body size was significantly smaller for bats and insectivores than for the other orders studied here, but significantly larger for mammals that utilized aquatic prey than for those restricted to terrestrial prey.

Main conclusions

The island rule appears to be a pervasive pattern, exhibited by mammals from a broad range of orders, functional groups and time periods. There remains, however, much scatter about the general trend; this residual variation may be highly informative as it appears consistent with differences among species, islands and environmental characteristics hypothesized to influence body size evolution in general. The more pronounced gigantism and dwarfism of palaeo‐insular mammals, in particular, is consistent with a hypothesis that emphasizes the importance of ecological interactions (time in isolation from mammalian predators and competitors was 0.1 to > 1.0 Myr for palaeo‐insular mammals, but < 0.01 Myr for extant populations of insular mammals). While ecological displacement may be a major force driving diversification in body size in high‐diversity biotas, ecological release in species‐poor biotas often results in the convergence of insular mammals on the size of intermediate but absent species.     

CYP17 mutation E305G causes isolated 17,20-lyase deficiency by selectively altering substrate binding

Cytochrome p450c17 (CYP17) converts the C21 steroids pregnenolone and progesterone to the C19 androgen precursors dehydroepiandrosterone (DHEA) and androstenedione, respectively, via sequential 17alpha-hydroxylase and 17,20-lyase reactions. Disabling mutations in CYP17 cause combined 17alpha-hydroxylase/17,20-lyase deficiency, but rare missense mutations cause isolated loss of 17,20-lyase activity by disrupting interactions of redox partner proteins with CYP17. We studied an adolescent male with clinical and biochemical features of isolated 17,20-lyase deficiency, including micropenis, hypospadias, and gynecomastia, who is homozygous for CYP17 mutation E305G, which lies in the active site. When expressed in HEK-293 cells or Saccharomyces cerevisiae, mutation E305G retains 17alpha-hydroxylase activities, converting pregnenolone and progesterone to 17alpha-hydroxysteroids. However, mutation E305G lacks 17,20-lyase activity for the conversion of 17alpha-hydroxypregnenolone to DHEA, which is the dominant pathway to C19 steroids catalyzed by human CYP17 (the delta5-steroid pathway). In contrast, mutation E305G exhibits 11-fold greater catalytic efficiency (kcat/Km) for the cleavage of 17alpha-hydroxyprogesterone to androstenedione compared with wild-type CYP17. We conclude that mutation E305G selectively impairs 17,20-lyase activity for DHEA synthesis despite an increased capacity to form androstenedione. Mutation E305G provides genetic evidence that androstenedione formation from 17alpha-hydroxyprogesterone via the minor delta4-steroid pathway alone is not sufficient for complete formation of the male phenotype in humans.     

Genome-wide association analysis of soluble ICAM-1 concentration reveals novel associations at the NFKBIK, PNPLA3, RELA, and SH2B3 loci

Soluble ICAM-1 (sICAM-1) is an endothelium-derived inflammatory marker that has been associated with diverse conditions such as myocardial infarction, diabetes, stroke, and malaria. Despite evidence for a heritable component to sICAM-1 levels, few genetic loci have been identified so far. To comprehensively address this issue, we performed a genome-wide association analysis of sICAM-1 concentration in 22,435 apparently healthy women from the Women's Genome Health Study. While our results confirm the previously reported associations at the ABO and ICAM1 loci, four novel associations were identified in the vicinity of NFKBIK (rs3136642, P = 5.4 × 10(-9)), PNPLA3 (rs738409, P = 5.8 × 10(-9)), RELA (rs1049728, P = 2.7 × 10(-16)), and SH2B3 (rs3184504, P = 2.9 × 10(-17)). Two loci, NFKBIB and RELA, are involved in NFKB signaling pathway; PNPLA3 is known for its association with fatty liver disease; and SH3B2 has been associated with a multitude of traits and disease including myocardial infarction. These associations provide insights into the genetic regulation of sICAM-1 levels and implicate these loci in the regulation of endothelial function.     

Characterization of the solubilization of lipid bilayers by surfactants

This communication addresses the state of aggregation of lipid-detergent mixed dispersions. Analysis of recently published data suggest that for any given detergent-lipid mixture the most important factor in determining the type of aggregates (mixed vesicles or mixed micelles) and the size of the aggregate is the detergent to lipid molar ratio in these aggregates, herein denoted the effective ratio, R_e. For mixed bilayers this effective ratio has been previously shown to be a function of the lipid and detergent concentrations and of an equilibrium partition coefficient, K, which describes the distribution of the detergent between the bilayers and the aqueous phase. We show that, similar to mixed bilayers, the size of mixed micelles is also a function of the effective ratio, but for these dispersions the distribution of detergent between the mixed micelles and the aqueous medium obeys a much higher partition coefficient. In practical terms, the detergent concentration in the mixed micelles is equal to the difference between the total detergent concentration and the critical micelle concentration (cmc). Thus, the effective ratio is equal to this difference divided by the lipid concentration. Transformation of mixed bilayers to mixed micelles, commonly denoted solubilization, occurs when the surfactant to lipid effective ratio reaches a critical value. Experimental evaluation of this critical ratio can be based on the linear dependence of detergent concentration, required for solubilization, on the lipid concentration. According to the ‘equilibrium partition model’, the dependence of the ‘solubilizing detergent concentration’ on the lipid concentration intersects with the lipid axis at −1/K, while the slope of this dependence is the critical effective ratio. On the other hand, assuming that when solubilization occurs the detergent concentration in the aqueous phase is approximately equal to the critical micelle concentration, implies that the above dependence intersects with the detergent axis at the critical micelle concentration, while its slope, again, is equal to the critical effective ratio. Analysis of existing data suggests that within experimental error both these distinctively different approaches are valid, indicating that the critical effective ratio at which solubilization occurs is approximately equal to the product of the critical micelle concentration and the distribution coefficient K. Since the nature of detergent affects K and the critical micelle concentration in opposite directions, the critical (‘solubilizing’) effective ratio depends upon the nature of detergent less than any of these two factors.     

Isolation and in vitro synthesis of trypsin from the biting fly,Stomoxys calcitrans

The synthesis of [3H]trypsinlike enzyme by the fat body was followed in Stomoxys calcitransin vitro using a radioimmunoassay (RIA) developed against mammalian trypsin. Using high specific activity [3H]valine, trypsinlike activity was followed in midgut epithelial cells, thoracic muscle, and fat body removed from sugar-fed flies. Excreta protease of S. calcitrans was partially purified using charge and hydroxylapatite gel chromatography. Seventy-five percent of the enzyme eluted from these gels was inhibited by tosyl-L-lysine chloromethyl ketone HCI (TLCK) and was classified as trypsinlike. Electrophoresis of the trypsinlike enzyme indicated that it was only 50% pure. Trypsinlike activity from S. calcitrans bound to α₁-globulin IV-I and formed a complex that was dissociated on a P-100 Bio-Gel column. Binding between the protease and the α₁-gobulin IV-I caused a 1.4-fold increase in the apparent molecular weight of the protease on the P-100 Bio-Gel column. Trypsinlike activity was characterized in the midgut and excreta by affinity binding to covalently linked TLCK and tosyl-L-lysine chloromethyl ketone HCI (TAME)Sepharose 4B gels. Between 50% and 55% of the excreta protease and 5669% of the midgut protease bound to the affinity gels and was trypsinlike. Protease activity that did not bind to the gels was not inhibited by TLCK and did not have the esterolytic activity of trypsin.