Endothelial cells on an aged subendothelial matrix display heterogeneous strain profiles in silico

Within the artery intima, endothelial cells respond to mechanical cues and changes in subendothelial matrix stiffness. Recently, we found that the aging subendothelial matrix stiffens heterogeneously and that stiffness heterogeneities are present on the scale of one cell length. However, the impacts of these complex mechanical micro-heterogeneities on endothelial cells have not been fully understood. Here, we simulate the effects of matrices that mimic young and aged vessels on single- and multi-cell endothelial cell models and examine the resulting cell basal strain profiles. Although there are limitations to the model which prohibit the prediction of intracellular strain distributions in alive cells, this model does introduce mechanical complexities to the subendothelial matrix material. More heterogeneous basal strain distributions are present in the single- and multi-cell models on the matrix mimicking an aged artery over those exhibited on the young artery. Overall, our data indicate that increased heterogeneous strain profiles in endothelial cells are displayed in silico when there is an increased presence of microscale arterial mechanical heterogeneities in the matrix.     

Novel metabolites in phenanthrene and pyrene transformation by Aspergillus niger.

Aspergillus niger, isolated from hydrocarbon-contaminated soil, was examined for its potential to degrade phenanthrene and pyrene. Two novel metabolites, 1-methoxyphenanthrene and 1-methoxypyrene, were identified by conventional chemical techniques. Minor metabolites identified were 1- and 2-phenanthrol and 1-pyrenol. No 14CO2 evolution was observed in either [14C]phenanthrene or [14C]pyrene cultures.     

21-Hydroxylase deficiency: screening and incidence in Israel

BACKGROUND: Neonatal screening for congenital adrenal hyperplasia was introduced in 1977. However, even today only a few national screening programs exist and their cost effectiveness is still debatable. This study was conducted in order to evaluate the advisability of a national or regional screening program in Israel. METHODS: From June 1987 until December 1992 we screened a countrywide random sample of 113,846 newborns for 21-hydroxylase (21-OH) deficiency measuring 17alpha-OH progesterone (17-OHP) from blood spotted on filter paper. Between January 1993 and August 1995 we continued the screening program concentrating on the population of northern Israel. A total of 56,958 newborns were screened. We compared these findings with the incidence of 21-OH deficiency in the total population born in Israel during the years 1986-1991. RESULTS: In the countrywide screening program, 4 newborns (2 Arabs and 2 Jews) were found to have levels of 17-OHP between 409 and 2,049 nmol/l (2 males and 2 females). This constitutes a low incidence of 1 in 28,462 live births. In the north-Israel screening program 4 newborns (all Arabs) were detected (2 males and 2 females) constituting a much higher incidence of 1 in 14,240 live births. The data obtained from the archives revealed that the incidence of 21-OH deficiency nationwide during the years 1986-1991 was 1:19,000 live births, 1:30,000 for Jews and 1:8,000 for Arabs. The incidence of 21-OH deficiency among Arab newborns in the northern part of the country was as high as 1:5,000 (14:71,130). The female to male (F:M) ratio was 2.6:1 and the ratio of the salt-losing to the simple virilizing variant was 5:1. Two male patients were diagnosed prenatally, 21 patients (17 F and 4 M) during the first month after birth and 6 others subsequently. CONCLUSIONS: The high F:M ratio of 21-OH deficiency in the total population compared to a 1:1 ratio in our random screening programs suggests that 21-OH-deficient male patients in the general population might have been missed or died early due to a salt-losing crisis. The high incidence of this disease in the northern part of the country and especially among the Arabs, suggests that screening in this part of the country, especially among the Arab population, is warranted and might save the lives of some male patients.     

An Evidenced-Based Scale of Disease Severity following Human Challenge with Enteroxigenic Escherichia coli

Background

Experimental human challenge models have played a major role in enhancing our understanding of infectious diseases. Primary outcomes have typically utilized overly simplistic outcomes that fail to entirely account for complex illness syndromes. We sought to characterize clinical outcomes associated with experimental infection with enterotoxigenic Escherichia coli (ETEC) and to develop a disease score.

Methods

Data were obtained from prior controlled human ETEC infection studies. Correlation and univariate regression across sign and symptom severity was performed. A multiple correspondence analysis was conducted. A 3-parameter disease score with construct validity was developed in an iterative fashion, compared to standard outcome definitions and applied to prior vaccine challenge trials.

Results

Data on 264 subjects receiving seven ETEC strains at doses from 1x10⁵ to 1x10¹⁰ cfu were used to construct a standardized dataset. The strongest observed correlation was between vomiting and nausea (r = 0.65); however, stool output was poorly correlated with subjective activity-impacting outcomes. Multiple correspondence analyses showed covariability in multiple signs and symptoms, with severity being the strongest factor corresponding across outcomes. The developed disease score performed well compared to standard outcome definitions and differentiated disease in vaccinated and unvaccinated subjects.

Conclusion

Frequency and volumetric definitions of diarrhea severity poorly characterize ETEC disease. These data support a disease severity score accounting for stool output and other clinical signs and symptoms. Such a score could serve as the basis for better field trial outcomes and gives an additional outcome measure to help select future vaccines that warrant expanded testing in pivotal pre-licensure trials.     

Fluorescence microscopy and radiolabeling of C3 and C4 chloroplasts using diisothiocyanatostilbene disulfonic acid as a marker for the phosphate translocator

The usefulness of 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) for in-situ studies of the chloroplast phosphate translocator was evaluated by fluorescence microscopy and radiolabeling of spinach (Spinacia oleracea L.) (C₃ plant) and maize (Zea mays L.) (C₄ plant) chloroplasts. In maize mesophyll and bundle-sheath chloroplasts and in spinach chloroplasts that were either intact, broken or swollen, DIDS fluorescence was only associated with the chloroplast envelope. Intact chloroplasts often had fluorescent patches corresponding to concave regions of the chloroplast which we assume to be regions enriched in DIDS-binding sites.Incubation of intact or broken spinach chloroplasts or maize mesophyll chloroplasts with [³H₂]DIDS resulted in the labeling of a single polypeptide (relative molecular mass, M_r, 30 kDa) in the envelope fraction, in each case. Label in the stromal fraction was not detected when intact chloroplasts were incubated with [³H₂]DIDS. However, when broken chloroplasts were incubated with [³H₂]DIDS, several polypeptides of various molecular masses were labeled, but not the 30×31-kDa polypeptide. In thylakoid fractions from both broken and intact chloroplasts, a single 30×31-kDa polypeptide was labeled inconsistently. When a mixture of intact maize mesophyll and bundle-sheath chloroplasts was labeled with [³H₂]DIDS, extracts of whole chloroplasts displayed radioactivity only in the 30×31-kDa band.We conclude that DIDS is a valuable probe for the in-situ identification and characterization of the 30-kDa protein — the presumptive phosphate translocator — in C₃ and C₄ chloroplasts since DIDS (1) does not penetrate the inner membrane of the envelope of intact chloroplasts and, therefore, (2) does not bind internal sites in intact chloroplasts, and (3) only binds the 30-kDa protein in the inner membrane of the envelope.Abbreviations CBB Coomassie brilliant blue - DIC differential interference contrast optics - DIDS 4,4-diisothiocyanatostilbene-2,2-disulfonic acid - [³H₂]DIDS 1,2-ditritio-1,2-(2,2-disulfo-4,4-diisothiocyano)diphenylethane - kDa kilodalton - M_r relative molecular mass - PGA 3-phosphoglycerate - Pitranslocator phosphate translocator - SDS sodium dodecyl sulfate     

Molecular cloning of human genes for serum amyloid A

Three human DNA fragments hybridizing to a mouse cDNA plasmid for the acute phase protein amyloid A have been isolated from the human lambda Charon 4A phage library. Two of these recombinants, GSAA1 (12.8 kb insert) and GSAA2 (15.9 kb insert), share an apparently identical internal region of 9.7 kb while the third, GSAA3 (15.95-kb insert) shows different restriction enzyme fragments. Hybridization studies localize the coding region to single HindIII fragments and suggest that all coding information is present in these recombinants; these fragments have been subcloned into pBR322 and mapped for further study.     

Structure of a recombinant calmodulin from Drosophila melanogaster refined at 2.2-A resolution

The crystal structure of calmodulin (Mr 16,700, 148 residues) from Drosophila melanogaster as expressed in a bacterial system has been determined and refined at 2.2-A resolution. Starting with the structure of mammalian calmodulin, we produced an extensively refitted and refined model with a conventional crystallographic R value of 0.197 for the 5,239 reflections (F greater than or equal to 2 sigma (F)) within the 10.0-2.2-A resolution range. The model includes 1,164 protein atoms, 4 calcium ions, and 78 water molecules and has root mean square deviations from standard values of 0.018 A for bond lengths and 0.043 A for angle distances. The overall structure is similar to mammalian calmodulin, with a seven-turn central helix connecting the two calcium-binding domains. The "dumb-bell" shaped molecule contains seven alpha-helices and four "EF hand" calcium-binding sites. Although the amino acid sequences of mammalian and Drosophila calmodulins differ by only three conservative amino acid changes, the refined model reveals a number of significant differences between the two structures. Superimposition of the structures yields a root mean square deviation of 1.22 A for the 1,120 equivalent atoms. The calcium-binding domains have a root mean square deviation of 0.85 A for the 353 equivalent atoms. There are also differences in the amino terminus, the bend of the central alpha-helix, and the orientations of some of the side chains.     

PKCε promotes cardiac mitochondrial and metabolic adaptation to chronic hypobaric hypoxia by GSK3β inhibition

PKCε is central to cardioprotection. Sub-proteome analysis demonstrated co-localization of activated cardiac PKCε (aPKCε) with metabolic, mitochondrial, and cardioprotective modulators like hypoxia-inducible factor 1α (HIF-1α). aPKCε relocates to the mitochondrion, inactivating glycogen synthase kinase 3β (GSK3β) to modulate glycogen metabolism, hypertrophy and HIF-1α. However, there is no established mechanistic link between PKCε, p-GSK3β and HIF1-α. Here we hypothesized that cardiac-restricted aPKCε improves mitochondrial response to hypobaric hypoxia by altered substrate fuel selection via a GSK3β/HIF-1α-dependent mechanism. aPKCε and wild-type (WT) mice were exposed to 14 days of hypobaric hypoxia (45 kPa, 11% O(2)) and cardiac metabolism, functional parameters, p-GSK3β/HIF-1α expression, mitochondrial function and ultrastructure analyzed versus normoxic controls. Mitochondrial ADP-dependent respiration, ATP production and membrane potential were attenuated in hypoxic WT but maintained in hypoxic aPKCε mitochondria (P < 0.005, n = 8). Electron microscopy revealed a hypoxia-associated increase in mitochondrial number with ultrastructural disarray in WT versus aPKCε hearts. Concordantly, left ventricular work was diminished in hypoxic WT but not aPKCε mice (glucose only perfusions). However, addition of palmitate abrogated this (P < 0.05 vs. WT). aPKCε hearts displayed increased glucose utilization at baseline and with hypoxia. In parallel, p-GSK3β and HIF1-α peptide levels were increased in hypoxic aPKCε hearts versus WT. Our study demonstrates that modest, sustained PKCε activation blunts cardiac pathophysiologic responses usually observed in response to chronic hypoxia. Moreover, we propose that preferential glucose utilization by PKCε hearts is orchestrated by a p-GSK3β/HIF-1α-mediated mechanism, playing a crucial role to sustain contractile function in response to chronic hypobaric hypoxia.     

Is hemiepiphytism an adaptation to high irradiance? Testing seedling responses to light levels and drought in hemiepiphytic and non‐hemiepiphytic Ficus

The epiphytic growth habit in many Ficus species during their juvenile stages has commonly been hypothesized to be an adaptation for avoiding deep shade in the forest understory, but this has never been tested experimentally. We examined growth and ecophysiology in seedlings of three hemiepiphytic (Hs) and three non‐hemiepiphytic (NHs) Ficus species grown under different irradiance levels. Both Hs and NHs exhibited characteristics of high light requiring species, such as high plasticity to growth irradiance and relatively high maximum photosynthetic assimilation rates. Diurnal measurements of leaf gas exchange showed that Hs have much shorter active photosynthetic periods than NHs; moreover, leaves of Hs have lower xylem hydraulic conductivity but stronger drought tolerance as indicated by much lower rates of leaf diebacks during the drought treatment. Seedlings of NHs had 3.3‐ and 13.3‐fold greater height and biomass than those of Hs species after growing in the nursery for 5 months, indicating a trade‐off between growth and drought tolerance due to the conflicting requirements for xylem conductivity and cavitation resistance. This study does not support the shade‐avoidance hypothesis; rather, it suggests that the canopy regeneration in Hs is an adaptation to avoid alternative terrestrial growth‐related risks imposed to tiny Ficus seedlings. The NHs with terrestrial regeneration reduce these risks by having an initial burst of growth to rapidly gain relatively large seedling sizes, while in Hs seedlings more conservative water use and greater drought tolerance for surviving the canopy environment are intrinsically associated with slow growth.